Pavlo Mikheenko

• Mikheenko, Pavlo (2026). Artificial quantum brain: A bold proposal. Low Temperature Physics. ISSN 1063-777X. 52(7), s. 900–904. doi: 10.1063/10.0044252. Fulltekst i vitenarkiv Vis sammendrag

  The paper discusses the possibility of building an elemental unit of an artificial quantum brain using self-assembly, featuring resonant synchronization and the spontaneous development of an action-potential response to coherent electromagnetic radiation. This unit will be suitable for incorporation into bionic robotic systems and/or natural biological organisms. It is proposed that the unit be formed through the self-assembly of superconducting microtubules on a rigid polymer scaffolding, with a spatial periodicity of 9 μm, to allow synchronization by infrared radiation at this wavelength, making it compatible with the natural brains of biological organisms. The paper describes the available experiments on the controlled self-assembly of such microtubules. Additionally, it suggests methods for training the artificial brain unit and exploring its emerging quantum consciousness.

• Ali, Ahmed Farag; Inan, Nader; Laukkonen, Ruben & Mikheenko, Pavlo (2026). A Coherence–Dissipation Framework for Brain Dynamics and Consciousness. Entropy. 28(10). doi: 10.3390/e28101074. Fulltekst i vitenarkiv Vis sammendrag

  We develop a theoretical proposal linking vacuum stability and brain dynamics through superconductivity-inspired coherence, symmetry reduction, and the thermodynamic stabilization of low-entropy regimes. We take an unbroken SU(3) structure as a candidate stable residue of the low-temperature vacuum. At the neural level, we formulate a coarse-grained analog in which a two-fluid model with dissipative and coherence-supporting components describes brain dynamics. Specifically, the coherence-supporting component is proposed as a possible basis for the efficient binding and integration required to sustain a stable, unified conscious state. The proposal offers a common geometric language for relating physics and neuroscience with falsifiable signatures in coherence and state-dependent transitions. The main technical contribution is a computational algebraic model of conscious-state dynamics, where neural data are mapped to reconstructed state trajectories. Effective generators are inferred from those trajectories, and the two-fluid split is tested as a Cartan–root decomposition of su(3), with a rank-two commuting sector for coherence-preserving balance and six root directions for state transitions. This structure can be tested on neural data and contrasted with alternative dynamical models.

• Perilla, Ana Lucia Campana; Gomez-Bolivar, Jamie; Merroun, Mohamed; Joudeh, Nadeem; Saragliadis, Athanasios & Røyne, Anja [Vis alle 8 forfattere av denne artikkelen] (2024). Characterization of Bimetallic Pd-Fe Nanoparticles Synthesized in Escherichia coli. ACS Applied Bio Materials (AABM). 7(12), s. 8573–8589. doi: 10.1021/acsabm.4c01354. Fulltekst i vitenarkiv Vis sammendrag

  Biologically mediated nanoparticle (NP) synthesis offers a reliable and sustainable alternative route for metal NP production. Compared with conventional chemical and physical production methods that require hazardous materials and considerable energy expenditure, some microorganisms can reduce metal ions into NPs during standard metabolic processes. However, to be considered a feasible commercial option, the properties and inherent activity of bio-NPs still need to be significantly improved. In this work, we present an Escherichia coli-mediated synthesis method for catalytically active Pd–Fe NPs. The produced biogenic Pd–Fe NPs with varying Fe content were characterized using complementary analytical techniques to assess their size, composition, and structural properties. In addition, their catalytic performance was assessed by using standardized chemical reactions. We demonstrate that the combination of Pd with Fe leads to synergistic effects that enhance the catalytic performance of Pd NPs and make biogenic Pd–Fe NPs excellent potential substitutes for currently used catalysts. Briefly, the apparent rates for the model reaction of 4-nitrophenol reduction to 4-aminophenol catalyzed by Pd-based nanoparticles were as high as 0.1312 min–1 using bimetallic Pd–Fe NPs, which is far superior to the rates of monometallic Pd NPs counterparts. This study provides a feasible strategy for the synthesis of multimetallic Pd-based NPs using common microbial processes. It emphasizes the potential of biogenic Pd–Fe NPs as efficient and sustainable catalysts for hydrogenation reactions, offering an environmentally friendly synthesis for various applications, including wastewater treatment and the production of fine chemicals.

• Mikheenko, Pavlo (2024). Symphony in the Brain. Japanese Journal of Medical Science. ISSN 2996-2536. 2(1), s. 1–7. doi: 10.33140/JJMS.02.01.06. Fulltekst i vitenarkiv Vis sammendrag

  Despite impressive progress in quantum biology, many questions about perception, cognition, memory, and their relation to processing of information remain unanswered. Here is an attempt to draw a unified picture starting with the basic quantum- mechanical phenomenon of nano-superconductivity in the microtubules and extending it to quantum processing of information, and generation of coherent Josephson radiation. A model for the generation in the axons of neurons is suggested. Like in a symphony, but on frequencies ten orders of magnitude higher, the radiation forms resonant standing electromagnetic waves, which are defined by the anatomy, synchronize all the functions in organism, and are behind the memory, perception, and cognition of a living being. It is true that we are made of atoms, but we are coherent electromagnetic waves.

• Perilla, Ana Lucia Campana; Saragliadis, Athanasios; Mikheenko, Pavlo & Linke, Dirk (2023). Insights into the bacterial synthesis of metal nanoparticles. Frontiers in Nanotechnology. 5. doi: 10.3389/fnano.2023.1216921. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2023). Screening of Magnetic Field by Self-Assembled Mammalian and Fungal Microtubules. I Novosad, V (Red.), 2023 IEEE 13th International Conference Nanomaterials: Applications & Properties (NAP). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9798350329094. doi: 10.1109/NAP59739.2023.10310733. Fulltekst i vitenarkiv Vis sammendrag

  Microtubules are essential structural elements in living organisms, which form scaffolding of the cells and participate in transport of proteins and separation of chromosomes. They are highly ordered nanotubes built of two types of tubulin proteins and filled with water. It was suggested that additionally to the transport and mechanical functions, microtubules are crucial for the processing of information. Moreover, this processing is considered to be quantummechanical and even based on superconductivity. Previously, screening of magnetic field, which supports superconductivity, has been observed by magnetic force microscopy in the microtubules assembled from the mammalian tubulin. Here the study is extended to the fungal self-assembled microtubules. In spite of observed structural differences between the mammalian and fungal microtubules, both display full screening of magnetic field. The temporal scans reveal steady screening in the mammalian microtubules and a fluctuating screening in the fungal microtubules. The formation of links between the microtubules and their implication for the processing and transfer of information is discussed.

• Bazioti, Kalliopi; Løvvik, Ole Martin; Poulia, Anthoula; Carvalho, Patricia Almeida; Azar, Amin S. & Mikheenko, Pavlo [Vis alle 8 forfattere av denne artikkelen] (2022). Probing the structural evolution and its impact on magnetic properties of FeCoNi(AlMn)x high-entropy alloy at the nanoscale. Journal of Alloys and Compounds. ISSN 0925-8388. 910, s. 1–12. doi: 10.1016/j.jallcom.2022.164724. Fulltekst i vitenarkiv Vis sammendrag

  We report the first nanoscale investigation of FeCoNi(AlMn)x high-entropy alloys (HEAs) processed by laser metal deposition. The structural evolution of the alloy upon chemical composition variation (0.2 ≤ x ≤ 1.5) was investigated by combining imaging and spectroscopies in (scanning) transmission electron microscopy (S)TEM with density functional theory (DFT). A gradual change from a face-centered cubic (FCC) towards an ordered full-Heusler (L21) phase by increasing the Al and Mn contents was observed. Direct imaging and atomic-scale calculations revealed a nanoscale interplay between B2 and L21 ordered structures for x = 1.5, wherein the latter, Al and Mn occupy two different Wyckoff sites. By decreasing x, the FCC phase dominates exhibiting intense phase separation tendency, ordering phenomena, and nano-precipitation. Although not chemically discriminated, plasmon-peak splitting in low-loss electron energy loss spectra revealed the presence of two valence electron densities within the FCC phase. Lorentz TEM showed that the ordered nano-precipitates and nano-sized grains with a structure based on a tripled FCC unit cell are pinning-sites for magnetic domain walls and dislocations. All alloy compositions exhibited soft-magnetic behavior with coercivity (Hc) values< 1000 A/m. The FeCoNi(AlMn)1.5 alloy with L21/B2 nanostructure showed the highest magnetization (Ms) with relatively low Hc, attributed to the large magnetic moment of Mn and the synergistic effect of Mn-Al according to DFT, whilst ordering does not impose a negative effect. Phase separation trends within the FCC phase seem to decrease the Ms however, the overall impact on the magnetic behavior is not intense, opening up for new avenues for tuning FeCoNiAlMn properties through chemically-designed phase decomposition regimes.

• Mojarrad, Masih; Farhoudian, Sana & Mikheenko, Pavlo (2022). Superconductivity and Hydrogen Economy: A Roadmap to Synergy. Energies. 15(17), s. 1–12. doi: 10.3390/en15176138. Fulltekst i vitenarkiv Vis sammendrag

  Hydrogen as an energy carrier is a promising alternative to fossil fuels, and it becomes more and more popular in developed countries as a carbon-free fuel. The low boiling temperature of hydrogen (20 K or −253.15 °C) provides a unique opportunity to implement superconductors with a critical temperature above 20 K such as MgB2 or high-temperature superconductors. Superconductors increase efficiency and reduce the loss of energy, which could compensate for the high price of LH2 to some extent. Norway is one of the pioneer countries with adequate infrastructure for using liquid hydrogen in the industry, especially in marine technology where a superconducting propulsion system can make a remarkable impact on its economy. Using superconductors in the motor of a propulsion system can increase its efficiency from 95% to 98% when the motor operates at full power. The difference in efficiency is even greater when the motor does not work at full power. Here, we survey the applications of liquid hydrogen and superconductors and propose a realistic roadmap for their synergy, specifically for the Norwegian economy in the marine industry.

• Joudeh, Nadeem; Saragliadis, Athanasios; Koster, Gerbrand; Mikheenko, Pavlo & Linke, Dirk (2022). Synthesis methods and applications of palladium nanoparticles: A review. Frontiers in Nanotechnology. 4, s. 1–24. doi: 10.3389/fnano.2022.1062608. Fulltekst i vitenarkiv Vis sammendrag

  Palladium (Pd) is a key component of many catalysts. Nanoparticles (NPs) offer a larger surface area than bulk materials, and with Pd cost increasing 5-fold in the last 10 years, Pd NPs are in increasing demand. Due to novel or enhanced physicochemical properties that Pd NPs exhibit at the nanoscale, Pd NPs have a wide range of applications not only in chemical catalysis, but also for example in hydrogen sensing and storage, and in medicine in photothermal, antibacterial, and anticancer therapies. Pd NPs, on the industrial scale, are currently synthesized using various chemical and physical methods. The physical methods require energy-intensive processes that include maintaining high temperatures and/or pressure. The chemical methods usually involve harmful solvents, hazardous reducing or stabilizing agents, or produce toxic pollutants and by-products. Lately, more environmentally friendly approaches for the synthesis of Pd NPs have emerged. These new approaches are based on the use of the reducing ability of phytochemicals and other biomolecules to chemically reduce Pd ions and form NPs. In this review, we describe the common physical and chemical methods used for the synthesis of Pd NPs and compare them to the plant- and bacteria-mediated biogenic synthesis methods. As size and shape determine many of the unique properties of Pd NPs on the nanoscale, special emphasis is given to the control of these parameters, clarifying how they impact current and future applications of this exciting nanomaterial.

• Mikheenko, Pavlo; Jacquemin, M; Mojarrad, Masih & Mercier, Frederic (2022). Controlling dendritic flux avalanches by nanostructure of superconducting films, 2022 IEEE 12th International Conference Nanomaterials: Applications & Properties (NAP). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781665489829. s. SNMS01-1–SNMS01-5. doi: 10.1109/NAP55339.2022.9934256. Fulltekst i vitenarkiv Vis sammendrag

  Niobium Nitrate (NbN) superconducting films are extensively used in superconducting electronics, for example as basic element of single-photon microwave resonators. Here we report on direct visualisation of magnetic flux penetration into a NbN thin film deposited by High-Temperature Chemical Vacuum Deposition (HTCVD). The film is of the thickness of 90.8 nm. It is deposited at temperature of 1200 C on a single-crystal α-Al2O3 (0001) c-axis substrate (sapphire). The visualisation is done by Magneto-Optical imaging allowing to see directly distribution of magnetic flux in the superconductor. It is found that at low temperatures magnetic flux penetrates into the film in the form of dendritic flux avalanches. Moreover, the shape of dendritic avalanches appeared to be very unusual, previously not reported in the literature. The branches of avalanches persistently follow one specific direction in the plane of the film. To clarify the origin of this effect, high-resolution Scanning Electron Microscopy and Atomic Force Microscopy have been used in combination with the Fast Fourier Transform of the obtained images. It was found that the origin of the selected direction in the dendritic flux penetration is deep on the nanometre scale, namely in nano-channels formed by the merging NbN crystallites during their growth. In this way, nanostructure of the film directly controls dendritic flux avalanches in the superconductor. Varying conditions of deposition would allow actively changing superconducting properties of the films.

• Mikheenko, Pavlo (2022). Ideal diamagnetism in brain microtubules, 2022 IEEE 12th International Conference Nanomaterials: Applications & Properties (NAP). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781665489829. s. SNMS02-1–SNMS02-4. doi: 10.1109/NAP55339.2022.9934729. Fulltekst i vitenarkiv Vis sammendrag

  With mounting evidences of superconductivity in brain microtubules, a key experiment to support its existence would be a nanometer-scale mapping of microtubule magnetic properties. Magnetic force microscopy is a convenient instrument to perform such mapping. Previously, it has been used qualitatively resulting in the detection of strong diamagnetic response coming from the in-plane bundles of microtubules. This was preliminary associated with the feature of ideal diamagnetism and therefore superconductivity in the microtubules. Numerical arguments, however, were absent and it was unclear in what substance superconductivity resides. In order to clarify this, magnetic force microscopy was extended to force spectroscopy, which records magnetic signal as a function of distance from the surface. Moreover, the magnetic force microscopy was performed on cross-sections of microtubules investigating them individually. In order to do this, a special technique of sample preparation has been developed allowing orienting microtubules perpendicular to the substrate. The magnetic mapping revealed strong diamagnetism coming from the inside of microtubules. The analysis of recorded force spectroscopy curves has been performed analytically separating magnetic and van der Waals contributions to the signal. Following this, estimation of the signal expected for ideal diamagnetism has been obtained and compared with the signal coming from the microtubules. It is concluded that microtubules display the property of ideal diamagnetism. The substance, in which superconductivity develops, is likely to be the structured water.

• Poulia, Anthoula; Larsen, Aleksander Amble; Graff, Joachim Seland; Diplas, Spyridon; Gunnæs, Anette Eleonora & Mikheenko, Pavlo (2022). Imaging Magnetic Domain Structure of a High Entropy Alloy: Effect of Applied Magnetic Field, 2022 IEEE 12th International Conference Nanomaterials: Applications & Properties (NAP). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781665489829. s. NMM01-1–NMM01-5. doi: 10.1109/NAP55339.2022.9934250. Fulltekst i vitenarkiv Vis sammendrag

  High-Entropy Alloys (HEAs) are recently introduced materials consisting of numerous—at least five—elements in nearly equal-atomic concentrations. Studying them, previously unexplored phase fields in multidimensional phase diagrams are now being explored. The HEA concept is based on a thermodynamic balance between mixing entropy and enthalpy, which defines values of several critical parameters that determine the formation of simple or complicated phases. Physical properties, like magnetism, are of great interest for these materials, even though they have not been extensively analyzed so far. Particularly, the exploration of the magnetic domain structure and its correlation with the micro- and nano-structural features of the materials is of high scientific value. In this work, we study the influence of the magnetic history on the alteration of the magnetic domain patterns in polycrystalline FeCoNiAl0.9Mn0.9 High Entropy Alloy (HEA). For the study, we introduce a combinatorial method of Electron Backscatter Diffraction and Magnetic Force Microscopy imaging, which reveals specific magnetic domain structures in the grains of different crystallographic orientations. It is found that in the HEA polycrystal, an increase of the applied magnetic field affects the formation of magnetic domains and leads to a transition from a labyrinth-like pattern to a dotted domain configuration, which is expressed differently in the differently oriented grains.

• Xu, Yan; Suo, Hongli; Qureishy, Thomas; Grivel, Jean-Claude; Mikheenko, Pavlo & Liu, Min [Vis alle 13 forfattere av denne artikkelen] (2021). Systematic research on the effect of both positive and negative mismatch dopants in double-doped YBCO superconducting films. Journal of the European Ceramic Society. ISSN 0955-2219. 41, s. 480–487. doi: 10.1016/j.jeurceramsoc.2020.07.074. Fulltekst i vitenarkiv Vis sammendrag

  We report a novel doping strategy for YBa2Cu3O7-x (YBCO) superconducting films by using a positive mismatch, Ba2YNbO6 (BYNO), and a negative mismatch, LaAlO3 (LAO), simultaneously. Double doping can significantly reduce the c-strain in the YBCO film by canceling the strain between the two dopants. By systematically optimizing the doping amount of both BYNO and LAO, it was found that BYNO and LAO do not act equally. The microstructure and distribution of both BYNO and LAO were investigated with magneto-optic microscopy and scanning electron microscopy. The effect of BYNO and LAO on pinning was confirmed. The results of this study will help select appropriate positive mismatch and negative mismatch dopants, which is fundamental to the design and fabrication of pinning centers to fit different application scenarios.

• Mojarrad, Masih; Hamid, Jouan; Perilla, Ana Lucia Campana; Dang, V.S.; Crisan, A. & Mikheenko, Pavlo (2021). Using magnetic nanoparticles to improve flux pinning in YBa2Cu3Ox films, 2021 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2021). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781665439077. s. SNMS01-1–SNMS01-5. doi: 10.1109/NAP51885.2021.9568543. Fulltekst i vitenarkiv Vis sammendrag

  Superconductors application can lead to significant economic benefits, especially in combination with use of liquid hydrogen, which is becoming an important part of the renewable energy economy. While many traditional superconductors cannot operate in liquid hydrogen, new materials, like high-temperature superconductors and MgB2 perfectly suit this purpose. YBa 2 Cu 3 O x is one of the most used high-temperature superconductors. It can operate even in liquid nitrogen, at the temperature of 77.3 K, but has a strong advantage of enhanced critical current density at the boiling temperature of liquid hydrogen of 20 K. A disadvantage of this material is the absence of natural c-axis pinning centers defining its critical current density. A usual way to solve this problem is the introduction of artificial pinning centers in the form of nanoparticles. The nanoparticles, however, reduce the volume of the superconductor and can lead to the formation of high-angle grain boundaries detrimental for the critical current. Here we explore an approach of depositing magnetic nanoparticles on the surface of superconducting films, which neither reduce the volume of the superconductor nor create high-angle grain boundaries. The additional pinning by these nanoparticles is studied by recording magneto-optical images of the films.

• Perilla, Ana Lucia Campana; Joudeh, Nadeem; Linke, Dirk & Mikheenko, Pavlo (2021). Magnetic decoration of Escherichia coli loaded with Palladium nanoparticles, 2021 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2021). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781665439077. s. NCI01-1–NCI01-5. doi: 10.1109/NAP51885.2021.9568523. Fulltekst i vitenarkiv Vis sammendrag

  Palladium (Pd) is a scarce metal, which is able to catalyze a variety of important chemical reactions. In the bulk form, Pd is anomalous paramagnetic, but in the form of nanoparticles, it has been reported as ferromagnetic. Detecting the magnetism of Pd nanoparticles is, however, difficult due to their reduced dimension. In addition, the ferromagnetic nature is a size-dependent property and, for Pd, the strength of magnetism decreases with slight increments in size. A “green” methodology for the preparation of small Pd nanoparticles was followed in this study. It is based on the ability of bacteria to take up Pd 2+ ions from its surrounding solution and to enzymatically reduce it to metallic Pd 0 nanoparticles. The efficiency of the production can be determined by transmission electron microscopy and, as a new technique, magnetic force microscopy. Notwithstanding, the study of nanoparticles of the size of just a few nanometers with these techniques is still difficult. Here we present a methodology for the enhancement of the magnetic signal of biologically produced Pd-based nanoparticles through the decoration of Escherichia coli bacteria cross-sections with Fe nanoparticles. This methodology allows the visualization of bacteria that are loaded with magnetic nanoparticles even when conventional transmission electron microscopy has difficulties to resolve them inside the microorganisms.

• Larsen, Aleksander Amble; Poulia, Anthoula; Azar, Amin S.; Bazioti, Kalliopi; Carvalho, Patricia Almeida & Gunnæs, Anette Eleonora [Vis alle 9 forfattere av denne artikkelen] (2021). Identifying Magnetic Phases in Additively Manufactured High-Entropy Alloy FeCoNiAlxMnx, 2021 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2021). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781665439077. s. NMM03-1–NMM03-4. doi: 10.1109/NAP51885.2021.9568591. Fulltekst i vitenarkiv Vis sammendrag

  High-Entropy Alloys are advanced technological materials composed of several (typically five) elements in nearly equal atomic concentration. By forming these alloys, previously unknown phase fields of multidimensional phase diagrams are explored. The large number of possible substitutions of constituent elements on crystal lattice sites justifies the dominant contribution of mixing entropy over enthalpy to the free energy reduction. This leads to the formation of phases, which otherwise could not be formed in alloys with fewer main alloying elements. Here we explore magnetic and compositional properties of a High-Entropy Alloy, namely FeCoNiAl x Mn x (0.05 ≤ x ≤ 3.08), composed of magnetic (Fe, Co, Ni) and non-magnetic elements (Al, Mn). By magnetic force microscopy of a selected area, it is observed that for intermediate to low Al and Mn contents, the alloy splits in two major crystallographic phases with different magnetic properties. Elemental maps of the same area were recorded with energy dispersive spectroscopy and scanning electron microscopy. Counterintuitively, it was found that the phase rich in non-magnetic Al has stronger magnetism than the phase rich in Fe. This work showcases possible applications of the here presented HEAs as soft magnetic materials in functional magnetic elements.

• Mikheenko, Pavlo (2021). Magnetic Force Microscopy of Brain Microtubules, 2021 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2021). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781665439077. s. SNMS02-1–SNMS02-4. doi: 10.1109/NAP51885.2021.9568538. Fulltekst i vitenarkiv Vis sammendrag

  Being biological object, microtubules attract significant attention in physics, since it is believed that they are responsible for quantum processing of information in the brain. There were, however, no direct experiments checking such a statement. Recently, strong advancement in quantum computing took place utilizing properties of superconductors at low temperatures. Following this progress, it was proposed that brain microtubules are superconducting at room temperature allowing quantum processing of information. Moreover, the evidence of room-temperature superconductivity in brain slices containing microtubules was obtained by electrical transport measurements, and even specific scenario of quantum processing in the microtubules has been suggested. These results, however, are not yet accepted by the scientific community as there are no known attempts to reproduce them. Another step in proving superconductivity would be confirming ideal diamagnetism of microtubules, since ideal diamagnetism is more fundamental property of superconductivity than perfect conductivity, some features of which were seen indirectly, or the existence of energy gap, which was already confirmed by the transport measurements. Here brain microtubules are examined by the magnetic force microscopy. The evidence of strong diamagnetism and its sensitivity to the water content in the microtubules is obtained. This gives another strong argument in favor of the concept suggesting superconductivity-based quantum processing of information in living organisms.

• Mikheenko, Pavlo; Baba, Elbruz Murat & Karazhanov, Smagul (2020). Electrical and Magnetic Behavior of GdOH Thin Films: A Search for Hydrogen Anion Superconductivity, Microstructure and Properties of Micro- and Nanoscale Materials, Films, and Coatings (NAP 2019) Selected Articles from the International Conference on Nanomaterials: Applications and Properties, (NAP 2019). Springer Nature. ISSN 9789811517419. s. 1–7. doi: 10.1007/978-981-15-1742-6_1. Fulltekst i vitenarkiv Vis sammendrag

  Anomalous resistive and magnetic behavior of GdOH thin films, which belong to the novel class of materials known as oxyhydrides, is reported. The oxyhydrides contain hydrogen in its rare negatively-charged anion state in combination with oxygen, which is also in the anion state. A range of GdOH films prepared on glass and single-crystalline substrates demonstrate a resistive transition from an insulating to conducting state with decrease of resistance starting as high as at about 200 K. At room temperature, the resistance per square area for the best GdOH films of the thickness of 200 nm is about 100 Ω, which is close to the resistance of the films of high-temperature superconductors of similar thickness. Apparent zero resistance is observed at about 40 K. Magneto-optical imaging registers effect of trapping magnetic flux typical for the superconducting state. The possible anion superconductivity is discussed in connection with recently published papers on near-room-temperature superconductivity in hydrides at high pressure and hydrogen-based superconductivity in biological systems.

• Claxton, James Benedict; Joudeh, Nadeem; Røyne, Anja; Linke, Dirk & Mikheenko, Pavlo (2020). Sequential magnetic mapping of bacteria loaded with Pd-Fe nanoparticles, 2020 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2020). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781728185064. s. 01NIC01-1–01NIC01-5. doi: 10.1109/NAP51477.2020.9309619. Fulltekst i vitenarkiv Vis sammendrag

  Magnetic nanoparticles are of widespread use in nanotechnology. One of the most unusual are magnetic palladium nanoparticles that combine magnetism with high catalytic activity. These nanoparticles could be obtained biologically by exposing bacteria to a palladium salt. Due to their small size and weak magnetism, however, it is challenging to measure their magnetic properties. One of the solutions to enhance their magnetism is to incorporate a small amount of iron atoms into them. After this procedure, the nanoparticles together with bacteria can be embedded in resin and characterized by the technique of magnetic force microscopy. This technique allows imaging cross-sections of the bacteria with nanoparticles, but cannot give information from the depth of the sample. Here we report on an approach partially solving this problem. Its novelty lies in measurements of consecutive thin slices of resin, which allows mapping cross-sections of individual bacteria and different parts of the material surrounding the same bacterium. An interesting observed feature is the formation of magnetic chains of nanoparticles outside of the bacteria.

• Poulia, Anthoula; Azar, Amin S.; Svec, Peter; Bazioti, Kalliopi; Belle, Branson & Gunnæs, Anette Eleonora [Vis alle 8 forfattere av denne artikkelen] (2020). Nanoscale Magnetic Properties of Additively Manufactured FeCoNiAlxMnx High-Entropy Alloys, 2020 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2020). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781728185064. s. 01NMM02-1–01NMM02-5. doi: 10.1109/NAP51477.2020.9309571. Fulltekst i vitenarkiv Vis sammendrag

  Magnetic properties of High-Entropy Alloys based on the Fe-Co-Ni-Al-Mn system are reported. High-Entropy Alloys are cutting-edge technological materials containing five or more elements in relatively high concentrations (5–35 at.%) within one or several solid-state solutions. These solutions are stabilized at the nanometer scale due to the high contribution of the mixing entropy to the Gibbs free energy, which can overcome the enthalpic contribution. Two magnetic alloys are found in FeCoNiAlxMnx (1.6 at.%  x  7.8 at.%) samples processed by laser metal deposition. The magnetic techniques used to screen the materials were magneto-optical imaging and magnetic force microscopy. The former allows characterizing magnetic properties within the mm-μm scale, while the latter is efficient down to the nanometer scale. Magnetic screening confirms the importance of the nanostructure in defining magnetic properties of the alloys, and the trends in the magnetic behavior as a function of the alloy composition are revealed. The experimental results suggest that it is possible to form unique alloys, which may outperform conventional magnetic materials used in a variety of applications such as transformers, screening shields and wind power generators.

• Perilla, Ana Lucia Campaña; Joudeh, Nadeem; Høyer, Henrik; Røyne, Anja; Linke, Dirk & Mikheenko, Pavlo (2020). Probing van der Waals and magnetic forces in bacteria with magnetic nanoparticles, 2020 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2020). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781728185064. s. 01NSSA03-1–01NSSA03-5. doi: 10.1109/NAP51477.2020.9309722. Fulltekst i vitenarkiv Vis sammendrag

  Bioinspired metal-based nanoparticles have potential uses in many applications, but before a possible commercial exploitation, it is important to clarify the pathways of their production and deposition inside the organisms, for example in bacteria. The technique of magnetic force microscopy (MFM) could be used to evaluate the nanoparticles magnetic properties, in addition to allowing tracing their location inside or outside of bacteria, which could help to understand pathways of their biosynthesis. In this work, using MFM and analyzing the interaction of magnetic tip with nanoparticles and bacteria imbedded in resin at different heights above the surface, and comparing gradients of forces recorded by magnetic and non-magnetic tips, a condition was found, which allows to measure pure magnetic response of Pd-Fe nanoparticles. For these nanoparticles, the interplay between magnetic and van der Waals forces is described at small distances to the surface. Experimental data are compared with simulations, based on the calculation of the distribution of magnetic field around a nanoparticle, which defines magnetic force acting on the MFM tip.

• Mikheenko, Pavlo (2020). Nano superconductivity and quantum processing of information in living organisms, 2020 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2020). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781728185064. s. 02SNS02-1–02SNS02-4. doi: 10.1109/NAP51477.2020.9309703. Fulltekst i vitenarkiv Vis sammendrag

  With the advance of superconducting quantum computing and the attempts of extending its operating range to higher temperatures, a special attention is paid to nanostructured quantum circuits. In particular, quasi one-dimensional quantum wires with phase slip centers are argued to be promising structures for the next generation of quantum computers. In its turn, this stimulates revisiting the question about the possibility of quantum processing of information in quasi one-dimensional structures in the nervous system, specifically the brain, in living organisms, especially in the light of recent findings that suggest robust room-temperature superconductivity in these structures. The early theories of superconductivity were in favor of its quasi one-dimensional nature, and the recent findings suggest that reducing dimensions of a system could be a good approach for increasing the critical temperature of a material. Here, based on experimental data, it is argued that both room-temperature superconductivity and quantum processing of information are possible in the microtubules that are abundant in the nervous system and form the scaffolding of every cell in advanced living organisms. The origin of superconductivity in microtubules, and the way in which quantum processing of information may take place in them, are discussed. The role of Josephson oscillations in processing and exchange of information is emphasized.

• Qviller, Atle Jorstad; Qureishy, Thomas; Xu, Y; Suo, H; Mozhaev, PB & Hansen, J.B. [Vis alle 9 forfattere av denne artikkelen] (2020). Scaling Behavior of Quasi-One-Dimensional Vortex Avalanches in Superconducting Films. Scientific Reports. doi: 10.1038/s41598-020-62601-y. Fulltekst i vitenarkiv Vis sammendrag

  Scaling behaviour of dynamically driven vortex avalanches in superconducting YBa2Cu3O7−δ films deposited on tilted crystalline substrates has been observed using quantitative magneto-optical imaging. Two films with different tilt angles are characterized by the probability distributions of avalanche size in terms of the number of moving vortices. It is found in both samples that these distributions follow power-laws over up to three decades, and have exponents ranging between 1.0 and 1.4. The distributions also show clear finite-size scaling, when the system size is defined by the depth of the flux penetration front – a signature of self-organized criticality. A scaling relation between the avalanche size exponent and the fractal dimension, previously derived theoretically from conservation of the number of magnetic vortices in the stationary state and shown in numerical simulations, is here shown to be satisfied also experimentally.

• Mikheenko, Pavlo; Baba, Elbruz Murat & Karazhanov, Smagul (2019). Electrical and Magnetic Behavior of GdOH Thin Films: a Search for Hydrogen Anion Superconductivity, Proceedings of the 2019 IEEE 9th International Conference on Nanomaterials: Applications & Properties (NAP-2019). Sumy State University. ISSN 9781728128306. s. 105–108. Fulltekst i vitenarkiv Vis sammendrag

  Anomalous resistive and magnetic behavior of GdOH thin films, which belong to novel class of materials known as oxyhydrides, is reported. The oxyhydrides contain hydrogen in its rare negatively-charged anion state in combination with oxygen, which is also in the anion state. A range of GdOH films prepared on glass and single-crystalline substrates demonstrate resistive transition from an insulating to conducting state with decrease of resistance starting as high as at about 200 K. At room temperature, the resistance per square area for the best GdOH films of the thickness of 200 nm is about 100 Ohm, which is close to the resistance of the films of high-temperature superconductors of similar thickness. Apparent zero resistance is observed at about 40 K. Magnetooptical imaging registers effect of trapping magnetic flux typical for the superconducting state. The possible anion superconductivity is discussed in connection with recently published papers on near-room-temperature superconductivity in hydrides at high pressure and hydrogen-based superconductivity in biological systems.

• Kashir, Alireza; Jeong, Hyeon-Woo; Lee, Gil-Ho; Mikheenko, Pavlo & Jeong, Yoon Hee (2019). Pulsed Laser Deposition of Rocksalt Magnetic Binary oxides. Thin Solid Films. ISSN 0040-6090. doi: 10.1016/j.tsf.2019.137606. Fulltekst i vitenarkiv Vis sammendrag

  Magnetic binary oxides with the rocksalt structure constitute an important class of materials for potential applications as electronic or electrochemical devices. Moreover, they often become a theoretical playground, due to the simple electronic and crystal structures, in the quest for novel phenomena. For these possibilities to be realized, a necessary prerequisite would be to grow atomically ordered and controllably-strained binary oxides on proper substrates. Here we systematically explore the use of pulsed laser deposition technique (PLD) to grow three basic oxides that have rocksalt structure but different chemical stability in the ambient atmosphere: NiO (stable), MnO (metastable) and EuO (unstable). By tuning laser fluence FL, an epitaxial single-phase NiO thin-film growth can be achieved in a wide range of growth temperatures 10 ≤ TG ≤750°C. At the lowest TG, the out-of-plane strain raises to 1.5%, which is five times higher than in NiO film grown at 750°C. MnO thin films that had long-range order were successfully deposited on the MgO substrates after appropriate tuning of deposition parameters. The growth of MnO phase was strongly influenced by FL and the TG. EuO films with satisfactory quality were deposited by PLD after oxygen availability had been minimized. Synthesis of EuO thin films at rather low TG = 350°C prevented thermally-driven lattice relaxation and allowed growth of strained films. Overall, PLD was a quick and reliable method to grow binary oxides with rocksalt structure in high quality that can satisfy requirements for applications and for basic research.

• Mikheenko, Pavlo (2019). Dislocations as Origin of High Critical Current Density in Bulk MgB2, Proceedings of the 2019 IEEE 9th International Conference on Nanomaterials: Applications & Properties (NAP-2019). Sumy State University. ISSN 9781728128306. s. 208–211. doi: 10.1109/NAP47236.2019.219079. Fulltekst i vitenarkiv Vis sammendrag

  MgB2 is an important superconducting material that could be used as a basis of liquid-hydrogen renewable energy economy. The distinctive property of this material is its very high critical current density in bulk reaching 106 A/cm2 . It is found that such a high critical current density is of nanoscale origin, and is linked to the pinning of magnetic flux quanta on grain boundaries. To advance this knowledge, a combination of atomic force microscopy, electron backscattered diffraction and SQUID magnetometry was used to clarify the exact dependence of critical current density on the density of dislocations in a cross-section of dense polycrystalline samples. It is found that in a system of randomly oriented grains, the dislocations residing in twist grain boundaries and their cross-points are responsible for the strong pinning in the material.

• Mikheenko, Pavlo (2019). Excitation of Vortex-Antivortex Pairs in Thin Superconducting Films and Superlattices. I Pogrebnjak, Alexander & Novosad, Valentine (Red.), Advances in Thin Films, Nanostructured Materials, and Coatings. Springer Nature. ISSN 9789811361333. s. 277–285. doi: 10.1007/978-981-13-6133-3_27. Fulltekst i vitenarkiv Vis sammendrag

  Direct imaging of the accumulation of magnetic flux and antiflux resulted from the excitation of vortex-antivortex pairs inside thin superconducting films is reported. Thin-film superconductors, like YBa2Cu3O7/PrBa2Cu3O7 superlattices or NbN films grown by pulsed laser deposition, were used in experiments. The superlattices provide enhanced pinning for vortices, facilitating imaging of accumulated flux, and feature nanoscale fractures ideal for excitation of vortex-antivortex pairs. The idea of the experiment is to record images using a specific magneto-optical mode that allows distinguishing between positive and negative magnetic field in the sample. Two types of flux-antiflux patterns are observed. In one type, flux and antiflux are entering on permanent defects, like nano-fractures formed in the process of film deposition. In another type, flux and antiflux patterns are formed by application of a strong localized magnetic field and not are linked to permanent defects. In the first type, the amount of flux and antiflux entering superconductor from the defect is strongly affected by an external magnetic field. In the second type, the permanently frozen pattern is hardly influenced by the field. An unusual and dramatic effect of the excitation of flux-antiflux dendritic avalanches is also reported.

• Mollatt, Hans Jakob; Qureishy, Thomas; Crisan, A.; Dang, V.S. & Mikheenko, Pavlo (2019). Channeling of Magnetic Flux in YBa2Cu3O7−δ Superlattices. I Pogrebnjak, Alexander & Novosad, Valentine (Red.), Advances in Thin Films, Nanostructured Materials, and Coatings. Springer Nature. ISSN 9789811361333. s. 287–295. doi: 10.1007/978-981-13-6133-3_28. Fulltekst i vitenarkiv Vis sammendrag

  We report an unusual effect of channeled magnetic flux motion in YBa2Cu3O7−δ/PrBa2Cu3O7−δ superlattices grown by pulsed laser deposition. Magneto-optical imaging reveals that flux moves along a set of parallel and perpendicular lines, while optical microscopy does not show any features on the surface that may cause this effect. In contrast, scanning electron microscopy registers sub-micron fractures in the superlattices, corresponding to the flux lines, but the magnetic flux channels are much wider than the width of these fractures. To further clarify the origin of flux channels, electrical transport measurements on the superlattices have been performed. Their current-voltage characteristics reveal the presence of distinctive branches related to the flux motion along the selective channels, following which magnetic flux can cross the sample in a shortest and least resistive way. The application of very large current overheated the superlattice along these channels evaporating superconducting material and exposing wider than in the superconductor fractures in the substrate. It is concluded that motion of flux in the channels is controlled not only by the presence of nano-fractures in YBa2Cu3O7−δ/PrBa2Cu3O7−δ, but also stresses developed in the superconducting material appearing due to the fracturing of the substrate.

• Kashir, Alireza; Jeong, Hyeon-Woo; Lee, Gil-ho; Mikheenko, Pavlo & Jeong, Yoon Hee (2019). Dielectric Properties of Strained Nickel Oxide Thin Films. Journal of the Korean Physical Society. ISSN 0374-4884. 74(10), s. 984–988. doi: 10.3938/jkps.74.984. Fulltekst i vitenarkiv Vis sammendrag

  In this paper, we briefly review the holographic dark energy model and introduce the idea that dark energy is a kind of thermal energy related to the quantum entanglement of the vacuum across a cosmic future event horizon. The holographic dark energy model comes from a theoretical attempt to apply the holographic principle to the dark energy problem and follows the idea that the short distance cut-off or ultraviolet (UV) cut-off is related to the long distance cut-off or infrared (IR) cut-off. The IR cut-off relevant to dark energy is the size of the future event horizon. This model gives a holographic dark energy comparable to the observational data. Though this model is in good agreement with observational data, some problems (non-locality, circular logic, causality problem, etc.) exist due to the use of the future event horizon as a present IR cut-off. These problems of the holographic dark energy model are considerably resolved using action principle and equations of motion. Finally, we discuss the relation between quantum entanglement and dark energy which is connected to the more fundamental relation between entanglement and gravity.

• Hjelmeland, Trude Bjørgås; Bazioti, Kalliopi; Gunnæs, Anette Eleonora; Volkov, Y & Mikheenko, Pavlo (2019). Effect of colossal magnetoresistance material La0.67Ca0.33MnO3 on superconducting properties of YBa2Cu3O7-δ thin films. Journal of Magnetism and Magnetic Materials. ISSN 0304-8853. 487. doi: 10.1016/j.jmmm.2019.165335. Fulltekst i vitenarkiv Vis sammendrag

  By specific design of the sample, in which SrTiO3 substrate is fully covered by a thin layer of the colossal magnetoresistive material La0.67Ca0.33MnO3 (LCMO) and the latter is partially covered by high-temperature superconductor YBa2Cu3O7-δ (YBCO), and by using multiple current and voltage contacts, direct evidence of the strong effect of LCMO on YBCO is obtained. It is found that LCMO strongly influences not only superconducting, but also normal state of YBCO, and it is argued that this is a consequence of the spin injection from the former to the latter. The effect of the deposition conditions and crystal orientation of YBCO layer on this effect is clarified. A surprising peak in the temperature dependence of resistance seen in ex-situ ab-plane oriented sample is explained as a combination of two effects: influence of spin-polarized electrons on superconductor below its critical temperature and the interface-controlled shift of Curie temperature of LCMO to low temperatures. Considering expected use of LCMO and YBCO in composite quantum computation circuits, their combination with another advanced quantum material, graphene, is explored.

• Zhao, Yue; Chu, Jingyuan; Qureishy, Thomas; Wu, Wei; Zhang, Zhiwei & Mikheenko, Pavlo [Vis alle 8 forfattere av denne artikkelen] (2018). Structural and superconducting characteristics of YBa2Cu3O7 films grown by fluorine-free metal-organic deposition route. Acta Materialia. ISSN 1359-6454. 144, s. 844–852. doi: 10.1016/j.actamat.2017.11.050. Fulltekst i vitenarkiv Vis sammendrag

  Microstructure and superconducting performance of YBa2Cu3O7 (YBCO) films deposited on LaAlO3 single crystal (LAO) substrates by a fluorine-free metal-organic deposition (FF-MOD) technique, have been studied by means of X-ray reciprocal space mapping (RSM), cross-sectional transmission electron microscopy (TEM) and magneto-optical (MO) imaging. Combining the X-ray diffraction and the TEM cross-sectional analysis, it is revealed that stacking faults, i.e. YBa2Cu4Ox intergrowths, and ab-plane twins are main defects in the FF-MOD YBCO films. Due to the highly epitaxial growth mechanism related to transient liquid phase, the LAO twinned substrate structure is also inherited in the FF-YBCO films. The low-density planar defects containing dislocations parallel to c-axis result in stripy patterns observed in the MO images. For comparison, the low-fluorine (LF) MOD film show a texture mosaic spread in the ab plane and is little influenced by the LAO twinning underneath, implying the severe structural disorder most likely associated with the large amount of small-angle grain boundaries. Moreover, the higher density of stacking faults was also detected by XRD θ−2θ scan in the LF-MOD film. It is suggested that associated partial dislocations formed at the boundary between the stacking faults and YBCO matrix act as strong linear (or dot) pinning centers. These structural characteristics are well in line with the better superconducting performance of the low fluorine-MOD film, in particular under external magnetic field at 77 K. This work offers an in-depth insight into the correlation between the microstructure and superconductivity in the MOD YBCO films.

• Mikheenko, Pavlo (2018). Possible superconductivity in the brain. Journal of Superconductivity and Novel Magnetism. ISSN 1557-1939. 32(5), s. 1121–1134. doi: 10.1007/s10948-018-4965-4. Fulltekst i vitenarkiv Vis sammendrag

  The unprecedented power of the brain suggests that it may process information quantum-mechanically. Since quantum processing is already achieved in superconducting quantum computers, it may imply that superconductivity is the basis of quantum computation in the brain too. Superconductivity could also be responsible for long-term memory. Following these ideas, the paper reviews the progress in the search for superconductors with high critical temperature and tries to answer the question about the superconductivity in brain. It focuses on recent electrical measurements of brain slices, in which graphene was used as a room-temperature quantum mediator, and argues that these measurements could be interpreted as providing evidence of superconductivity in the neural network of mammalian brains. The estimated critical temperature of superconducting network in the brain is rather high, 2022 ± 157 K. A similar critical temperature was predicted in the Little’s model for one-dimensional organic chains linked to certain molecular complexes. A reasonable suggestion is that superconductivity develops in microtubules inside the neurons of the brain.

• Qureishy, Thomas; Vestgården, Jørn Inge; Qviller, Atle Jorstad; Fjellvåg, Asbjørn Slagtern; Meckbach, Johannes Maximilian & Torgovkin, Andrii [Vis alle 11 forfattere av denne artikkelen] (2018). Energy of dendritic avalanches in thin-film superconductors. AIP Advances. 8:085128(8), s. 085128-1–085128-8. doi: 10.1063/1.5045682. Fulltekst i vitenarkiv Vis sammendrag

  A method for calculating stored magnetic energy in a thin superconducting film based on quantitative magneto-optical imaging is developed. Energy and magnetic moment are determined with these calculations for full hysteresis loops in a thin film of the superconductor NbN. Huge losses in energy are observed when dendritic avalanches occur. Magnetic energy, magnetic moment, sheet current and magnetic flux distributions, all extracted from the same calibrated magneto-optical images, are analyzed and discussed. Dissipated energy and the loss in moment when dendritic avalanches occur are related to each other. Calculating these losses for specific spatially-resolved flux avalanches is a great advantage, because of their unpredictable and non-reproducible nature. The relative losses in energy are much higher than the relative losses in moment.

• Hjelmeland, Trude Bjørgås; Volkov, Y & Mikheenko, Pavlo (2018). Effect of Spin Injection from Colossal Magnetoresistance Material into superconducting Thin Film of YBa2Cu3O7-x, 2018 IEEE 8th International Conference on Nanomaterials: Applications & Properties (NAP – 2018). Sumy State University. ISSN 9781538653333. s. 02TSSPN02-1–02TSSPN02-5. doi: 10.1016/j.jmmm.2019.165335. Fulltekst i vitenarkiv Vis sammendrag

  By specific design of the sample, in which SrTiO3 substrate is fully covered by a thin film of the colossal magnetoresistive material La0.67Ca0.33MnO3 (LCMO) and the latter is partially covered by high-temperature superconductor YBa2Cu3O7- (YBCO), and by using multiple current and voltage contacts, direct evidence of spin injection from LCMO to YBCO is obtained. It is found that spin-polarized electrons injected from LCMO strongly influence not only superconducting, but also normal state of YBCO. The effect of deposition conditions of LCMO and YBCO and the quality of the interface on the spin injection efficiency is clarified. A surprising peak in the temperature dependence of resistance seen on ex-situ sample is explained as combination of two effects: strong influence of spinpolarized electrons on superconductor just below its critical temperature and the interface-controlled shift of Curie temperature of LCMO to low temperatures. Considering expected use of LCMO and YBCO in composite quantum computation circuits, a possibility of their combination with another advanced quantum material, graphene, is explored.

• Mikheenko, Pavlo (2018). Excitation of Vortex-antivortex Pairs in Thin Superconducting Films, 2018 IEEE 8th International Conference on Nanomaterials: Applications & Properties (NAP – 2018). Sumy State University. ISSN 9781538653333. s. 03TFNMC08-1–03TFNMC08-4. doi: 10.1007/978-981-13-6133-3_27. Fulltekst i vitenarkiv Vis sammendrag

  Direct imaging of the accumulation of magnetic flux and antiflux resulted from the excitation of vortex-antivortex pairs inside thin superconducting films is reported. Thin-film superconductors, like YBa2Cu3O7PrBa2Cu3O7 superlattices or NbN films grown by pulsed laser deposition were used in experiments. The superlattices provide enhanced pinning for vortices, facilitating imaging of accumulated flux, and feature nanoscale fractures ideal for excitation of vortex-antivortex pairs. The idea of experiment is to record images using specific magneto-optical mode that allows distinguishing between positive and negative magnetic field in the sample. Two types of fluxantiflux patterns are observed. In one type, flux and antiflux are entering on permanent defects, like nano-fractures formed in the process of film deposition. In another type, flux and antiflux patterns are formed by application of strong localized magnetic field and not are linked to permanent defects. In first type, the amount of flux and antiflux entering superconductor from defect is strongly affected by external magnetic field. In the second type, the permanent frozen pattern is hardly influenced by the field. An unusual and dramatic effect of the excitation of flux-antiflux dendritic avalanches is also reported.

• Mollatt, Hans Jakob; Qureishy, Thomas; Crisan, A; Dang, V.S. & Mikheenko, Pavlo (2018). Flux Channeling in YBa2Cu3O7Superlattices, 2018 IEEE 8th International Conference on Nanomaterials: Applications & Properties (NAP – 2018). Sumy State University. ISSN 9781538653333. s. 03TFNMC09-1–03TFNMC09-4. doi: 10.1109/nap.2018.8915321. Fulltekst i vitenarkiv Vis sammendrag

  We report unusual effect of channeled magnetic flux flow in YBa2Cu3O7-PrBa2Cu3O7- superlattices grown by pulsed laser deposition. Magneto-optical imaging reveals that flux moves along a set of mutually perpendicular lines, while optical microscopy does not show any features on the surface that may cause this effect. In contrast, scanning electron microscopy registers corresponding to the flux lines, sub-micron fractures in the superlattices, but magnetic flux channels are much wider than width of these fractures. To further clarify origin of flux channels, electrical transport measurements on the superlattices have been performed. Their current-voltage characteristics reveal presence of distinctive branches related to the flux motion along the selective channels, following which magnetic flux can cross the sample in a shortest and less resistive way. The application of very large current overheated superlattice along these channels evaporating superconducting material and exposing wider than in superconductor cracks in the substrate. It is concluded that motion of flux in the channels is controlled not only by the presence of nano-fractures in YBa2Cu3O7- PrBa2Cu3O7-, but also stresses developed in superconducting material appearing due to fracturing of substrate.

• Mikheenko, Pavlo; Qureishy, Thomas; Mercier, Frederic; Jacquemin, M & Pons, M (2017). Dendritic flux avalanches in high-quality NbN superconducting films, Proceedings of the 2017 IEEE 7th International Conference on Nanomaterials: Applications & Properties (NAP-2017). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781538628102. s. 02NTF05-1–02NTF05-5. doi: 10.1109/nap.2017.8190366. Fulltekst i vitenarkiv Vis sammendrag

  Niobium nitride (NbN) thin films are extensively used in superconducting devices such as single-photon detectors, hot electron bolometers, microwave resonators and kinetic inductance detectors. The operation of these devices is strongly influenced by the quality of the films, especially by their resistivity and superconducting transition temperatures (Tc). NbN films have rather high Tc of ∼16.5 K and high resistivity of few hundreds micro-Ohm cm, which is perfect for operation of many superconducting devices. However, at low temperatures films are vulnerable to thermomagnetic instabilities in form of dendritic avalanches promoted by high resistivity in the normal state. Recently, new production route for NbN films has been established using high-temperature chemical vapor deposition (HTCVD). Transport measurements show low resistivity in normal state and suggest low level of lattice disorder. The highest for NbN Tc of 17.06 K was also reported in the films grown by HTCVD. According to previous study, these films should be thermo-magnetically stable. This work clarifies if it is the case and searches in one of them for dendritic flux avalanches. The nanoscale origin of avalanches is discussed.

• Fjellvåg, Asbjørn Slagtern; Hjelmeland, Trude Bjørgås; Mollatt, Hans Jakob; Qureishy, Thomas & Mikheenko, Pavlo (2017). Interplay between spin polarization and superconductivity in an ex-situ bilayer La0.67Ca0.33MnO3 - YBa2Cu3O7-x, Proceedings of the 2017 IEEE 7th International Conference on Nanomaterials: Applications & Properties (NAP-2017). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781538628102. s. 02NTF02-1–02NTF02-5. Fulltekst i vitenarkiv Vis sammendrag

  An anomalous magnetism is observed in an ex-situ bilayer of high-temperature superconductor YBa2Cu3O7-δ and colossal magnetoresistive material La0.67Ca0.33MnO3. The magnetism results in strong in-plane anisotropy of the resistance and surprising peak in the temperature dependence of resistance below superconducting transition associated with the interplay between superconductivity and establishment of the magnetic order. Magneto-optical-imaging reveals a stripy magnetic structure in the bilayer linked with unusual behavior of the resistance. The magnetization measurements demonstrate strong and irreversible magnetism, which is likely associated with reorientation of the magnetic moment of interface. The observed non-linear resistance could find practical use exploring further link between superconductivity and magnetism of the interface.

• Mikheenko, Pavlo (2017). Nanomaterials for renewable energy economy, Proceedings of the 2017 IEEE 7th International Conference on Nanomaterials: Applications & Properties (NAP-2017). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781538628102. s. 03NE05-1–03NE05-5. doi: 10.1109/nap.2017.8190236. Fulltekst i vitenarkiv Vis sammendrag

  Renewal energy economy relies on a range of novel materials for efficient production, distribution and consumption of energy. Nano science is playing increasingly important role in design and production of these materials. Examples of nano applications in energy sector are given following original research on materials for energy economy with focus on transmission of energy. The research is focused on nano-modified superconductors and novel thermo-insulators. A forecast for future activity is given, which is expected to lead to better materials, for example, superconductors with higher critical temperature and/or higher critical current density. The processes and equipment to process nano-materials are also discussed.

• Laliena, Carlos; Qureishy, Thomas; Martínez, Elena; Navarro, Rafael; Mikheenko, Pavlo & Johansen, Tom Henning [Vis alle 7 forfattere av denne artikkelen] (2017). Effect of ball milling on the local magnetic flux distribution and microstructure of in situ Fe/MgB2 conductors. Journal of Alloys and Compounds. ISSN 0925-8388. 717, s. 164–170. doi: 10.1016/j.jallcom.2017.05.083. Fulltekst i vitenarkiv Vis sammendrag

  The effects of the precursor milling energy on the superconducting and microstructural homogeneity of Fe-sheathed MgB2 monocore wires and tapes have been investigated. The conductors were produced by the powder-in-tube method using drawing and rolling deformation methods and in situ reaction. Combined magneto-optical, structural and magnetization measurements were performed on MgB2 superconducting tapes prepared from differently milled precursors revealing hidden mechanisms controlling their critical current density. Local degradation of the superconducting properties observed in some analysed conductors has been identified and correlated with microstructural observations.

• Jung, Soon-Gil; Shin, Soohyeon; Jang, Harim; Mikheenko, Pavlo; Johansen, Tom Henning & Park, Tuson (2017). Effects of magnetic impurities on upper critical fields in the high-T c superconductor La-doped CaFe2As2. Superconductors Science and Technology. ISSN 0953-2048. 30:085009(8), s. 1–8. doi: 10.1088/1361-6668/aa766c. Fulltekst i vitenarkiv Vis sammendrag

  We investigate the effects of magnetic impurities on the upper critical field (μ 0 H c2) in La-doped CaFe2As2 (LaCa122) single crystals. The magnetic field dependency of the superconducting transition temperature (T c) for LaCa122 is rapidly suppressed at low fields up to ~1 kOe despite its large μ 0 H c2(0) value on the order of tens of Tesla, resulting in a large positive curvature of μ 0 H c2(T) near T c. The magnetization hysteresis (M–H) loop at temperatures above T c shows a ferromagnetic-like signal and the M(H) value rapidly increases with increasing magnetic field up to ~1 kOe. Taken together with the linear suppression of T c with the magnetization in the normal state, these results suggest that the large upward curvature of μ 0 H c2(T) near T c in La-doped CaFe2As2 mainly originates from the suppression of superconductivity due to the presence of magnetic impurities. © 2017 IOP Publishing

Se alle arbeider i NVA

• Ali, Ahmed Farag; Inan, Nader; Laukkonen, Ruben & Mikheenko, Pavlo (2026). Could meditation reveal an SU(3) symmetry shared by the observer and the universe? doi: https:/phys.org/news/2026-10-meditation-reveal-su3-symmetry-universe.html#google_vignette. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2026). A quantum description of nervous system. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2025). Nanosuperconductivity in biological systems. Fulltekst i vitenarkiv Vis sammendrag

  Nanosuperconductivity in biological systems P. Mikheenko Department of Physics, University of Oslo, Oslo, Norway pavlo.mikheenko@fys.uio.no Abstract. Superconductivity is basic quantum-mechanical phenomenon with multiple technological applications, among which is quantum computing [1]. It is usually associated with metals and low temperatures but theoretically was extended to room temperature, organic, and biological materials [2,3]. For room-temperature superconductivity, an unconventional mechanism is needed, preferably in a system with reduced dimensionality. The experimental attempts in search for such superconductivity are under the way. Here the experiments with microtubules, nanometer-scale quasi one-dimensional structures abundant in the brain are presented arguing that they are in the superconducting state at the room temperature. Complementing already published data on electrical transport [4] and magnetic [5] measurements, current research focuses on magnetic flux quantization and Josephson radiation coming from the connections of microtubules in the neurons during the propagation of action potential [6-8]. A mechanism for such generation is suggested [6,8]. It is argued that nanoscale superconductivity is responsible for quantum processing of information in the microtubules [9], while coherent Josephson radiation helps synchronizing functions of living organisms. To put idea of the room temperature superconductivity on a solid basis, the values of its main parameters like energy gap, critical temperature, magnetic penetration depth, and coherence length are estimated [6,8]. The results could improve understanding of quantum-mechanical basis of biological systems in a humid and warm environment arguing that nanoscale room-temperature superconductivity perfectly survives in this environment and plays important role in the functioning of living organisms. The application of this concept to practical construction of artificial quantum brain will be discussed [10]. 1. H.-L. Huang, D. Wu, D. Fan, X. Zhu, “Superconducting Quantum Computing: A Review,” Science China Information Sciences, vol. 63, 180501, July 2020. 2. W. A. Little, “Possibility of synthesizing an organic superconductor,” Phys. Rev., vol. 134, pp. A1416–A1424, June 1964. 3. E. H. Halperin, and A. A. Wolf, “Speculations of superconductivity in biological and organic systems,” In: Advances in Cryogenic Engineering, vol. 17, Boston, MA: Springer, 1972. 4. P. Mikheenko, “Possible superconductivity in the brain,” J. Supercond. Novel Magn., vol. 32, pp. 1121–1134, Dec. 2018. https://doi.org/10.1007/s10948-018-4965-4 5. P. Mikheenko, “Ideal Diamagnetism in Brain Microtubules,” IEEE Xplore Digital Library, 9934729, November 2022. https://doi.org/10.1109/NAP55339.2022.9934729 6. P. Mikheenko, “Symphony in the brain.” Japanese Journal of Medical Science, vol. 2(1), 01-07, June 2024. https://www.opastpublishers.com/open-access-articles/symphony-in-the-brain.pdf. 7. P. Mikheenko, Superconductivity in self-assembled microtubules. Preprint, Research Gate, February 2023. https://doi.org/10.13140/RG.2.2.20573.28649/1. 8. P. Mikheenko, Nanoscale Room-Temperature Superconductivity in Biological Systems, IEEE Xplore Digital Library, 10739752, November 2024. https://doi.org/10.1109/NAP62956.2024.10739752. 9. P. Mikheenko, Nano superconductivity and quantum processing of information in living organisms, IEEE Xplore Digital Library 9309703, January 2021. https://doi.org/10.1109/NAP51477.2020.9309703 10. P. Mikheenko, Artificial quantum brain. Preprint. Research Gate, January 2025. https://www.researchgate.net/publication/387867028_Artificial_quantum_brain DOI: 10.13140/RG.2.2.31529.51046

• Perilla, Ana Lucia Campana; Saragliadis, Athanasios; Merroun, Mohamed; Rachel, Reinhard; Mikheenko, Pavlo & Linke, Dirk (2025). Microbial strategies for tailored metal nanoparticle production. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2024). Nanoscale Room-Temperature Superconductivity in Biological Systems, 2024 IEEE 14th International Conference on Nanomaterials: Application & Properties (NAP). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9798350380125. s. SNMS01-1–SNMS01-5. doi: 10.1109/NAP62956.2024.10739752. Fulltekst i vitenarkiv Vis sammendrag

  Superconductivity is a quantum-mechanical phenomenon with multiple technological applications among which is quantum computing. It is usually associated with metals and low temperatures, but theoretically was extended to room temperature, organic, and biological matter. To achieve room-temperature superconductivity, an unconventional mechanism in a system with reduced dimensionality is likely to be necessary. Experimental attempts in search for it are under the way. Here the experiments with microtubules, nanometer-scale quasi one-dimensional structures abundant in the brain and nerve system are presented arguing that they are superconducting at the room temperature. Complementing data on electrical transport and magnetic measurements, the paper focuses on the magnetic flux quantization and Josephson effect revealed by the electromagnetic radiation coming from the connections of microtubules during the propagation of action potential in the axons of the nerve cells. A mechanism for such generation is suggested. It is argued that nanoscale superconductivity is responsible for the quantum processing of information in the living organisms, and the coherent Josephson radiation helps synchronizing their functions. The values of main parameters for the room-temperature superconductor are estimated and given in the paper. The interpretation of the behavior of microtubules in terms of room-temperature superconductivity could strengthen understanding of the quantum nature of biological systems.

• Mikheenko, Pavlo (2024). Nanoscale Room-Temperature Superconductivity in Biological Systems. Fulltekst i vitenarkiv
• Perilla, Ana Lucia Campana; Saragliadis, Athanasios; Merroun, Mohamed; Mikheenko, Pavlo & Linke, Dirk (2024). Microbial-metal interactions for biosynthesis of tailored metal nanoparticles. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2024). Nanosuperconductivity and nanophotonics in biological systems. Fulltekst i vitenarkiv
• Campana, A.; Joudeh, Nadeem; Merroun, Mohamed; Gomez-Bolivar, Jamie; Linke, Dirk & Mikheenko, Pavlo (2023). Biosynthesis and characterization of Palladium-based nanoparticles produced by Escherichia coli. Fulltekst i vitenarkiv
• Perilla, Ana Lucia Campana; Joudeh, Nadeem; Merroun, Mohamed; Gomez-Bolivar, Jamie; Linke, Dirk & Mikheenko, Pavlo (2023). Bacterial synthesis of Palladium nanoparticles. Fulltekst i vitenarkiv
• Perilla, Ana Lucia Campana; Joudeh, Nadeem; Merroun, Mohamed; Gomez-Bolivar, Jamie; Linke, Dirk & Mikheenko, Pavlo (2023). Bacterial synthesis of Palladium nanoparticles. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2023). Screening of magnetic field by self-assembled mammalian and fungi microtubules. Fulltekst i vitenarkiv Vis sammendrag

  Microtubules are essential structural elements in living organisms, which form scaffolding of the cells and participate in transport of proteins and separation of chromosomes [1]. They are highly ordered nanotubes built of two types of tubulin proteins, and filled with water [2]. It was suggested that additionally to the transport and mechanical functions, microtubules are crucial for the processing of information [3]. Moreover, this processing is considered to be quantum-mechanical [3] and even based on superconductivity [4]. Previously, screening of the magnetic field, which supports superconductivity, has been observed by the magnetic force microscopy in the microtubules assembled from the mammalian tubulin [5]. Here the study is extended to the fungi self-assembled microtubules. In spite of observed structural differences between the mammalian and fungi microtubules, both display full screening of magnetic field. The temporal scans reveal steady screening in the mammalian microtubules and a fluctuating screening in the fungi microtubules. The formation of links between the microtubules and their implication for the processing of information is discussed. [1] D. A. Fletcher and R. D. Mullins, “Cell mechanics and the cytoskeleton,” Nature, vol. 463, pp. 485–492, January 2010. [2] S. Sahu, S. Ghosh, B. Ghosh, K. Aswani, K. Hirata, D. Fujita, and A. Bandyopadhyay, “Atomic water channel controlling remarkable properties of a single brain microtubule: Correlating single protein to its supramolecular assembly,” Biosens. Bioelectron., vol. 47, pp.141–148, September 2013. [3] S. Hameroff, “Quantum computation in brain microtubules? The Penrose–Hameroff ‘Orch OR’ model of consciousness,” Phil. Trans. R. Soc. A, vol. 356, pp. 1869-1896, August 1998. [4] P. Mikheenko, “Nano Superconductivity and Quantum Processing of Information in Living Organisms,” IEEE Xplore Digital Library 9309703, January 2021. [5] P. Mikheenko, “Ideal Diamagnetism in Brain Microtubules,” IEEE Xplore Digital Library, 9934729, November 2022.

• Jemterud, Torkild & Mikheenko, Pavlo (2023). Spesial: LK-99 Superlederen som slo ned som en bombe. [Radio]. NRK. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2023). Self-assembled microtubules: a possible quantum “grey matter” for artificial intelligence. Fulltekst i vitenarkiv Vis sammendrag

  It is believed that living organisms process information quantum-mechanically using microtubules [1,2]. In [2], this process is linked to superconductivity. Here experiments are reported, which directly visualize self-assembly of the microtubules in an extract from a mammalian brain and a fungi. The evidence of superconductivity is presented. The influence of nanoparticles on the self-assembly and the possibilities to use the network of the self-assembled microtubules as a “grey matter” for artificial intelligence will be discussed. 1. S. Hameroff Quantum computation in brain microtubules? The Penrose Hameroff ‘Orch OR’ model of consciousness, Phil. Trans. R. Soc. A. 356 1869–1896 (1998). https://doi.org/10.1098/rsta.1998.0254. 2. P. Mikheenko, Nano Superconductivity and Quantum Processing of Information in Living Organisms, IEEE Xplore Digital Library 9309703 (2021). https://doi.org/10.1109/NAP51477.2020.9309703.

• Perilla, Ana Lucia Campana; Joudeh, Nadeem; Merroun, Mohamed; Gomez-Bolivar, Jamie; Linke, Dirk & Mikheenko, Pavlo (2023). Biosynthesis and characterization of Palladium-based nanoparticles produced by Escherichia coli. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2023). Superconductivity: from Large Hadron Collider to quantum processing of information in living organisms. Fulltekst i vitenarkiv Vis sammendrag

  Superconductivity offers absolute zero of resistance and complete expulsion of magnetic flux. It is very valuable for technological applications. Its top achievement is in quantum computing. The unprecedented power of the brain suggests quantum-mechanical processing of information too. Here a search for superconductivity, on which quantum processing of information in living organisms could be based, is presented. Evidences of room-temperature superconductivity in biological systems are given. Implications for explaining consciousness and exchange of information using coherent infrared radiation will be discussed. Demonstrations of superconductivity are offered.

• Poulia, Anthoula; Larsen, Aleksander; Graff, Joachim Seland; Diplas, Spyridon; Gunnæs, Anette Eleonora & Mikheenko, Pavlo (2022). Imaging Magnetic Domain Structure of a High Entropy Alloy: Effect of Applied Magnetic Field. Fulltekst i vitenarkiv Vis sammendrag

  High-Entropy Alloys (HEAs) are recently introduced materials consisting of numerous—at least five—elements in nearly equal-atomic concentrations. Studying them, previously unexplored phase fields in multidimensional phase diagrams are now being explored. The HEA concept is based on a thermodynamic balance between mixing entropy and enthalpy, which defines values of several critical parameters that determine the formation of simple or complicated phases. Physical properties, like magnetism, are of great interest for these materials, even though they have not been extensively analyzed so far. Particularly, the exploration of the magnetic domain structure and its correlation with the micro- and nano-structural features of the materials is of high scientific value. In this work, we study the influence of the magnetic history on the alteration of the magnetic domain patterns in polycrystalline FeCoNiAl0.9Mn0.9 High Entropy Alloy (HEA). For the study, we introduce a combinatorial method of Electron Backscatter Diffraction and Magnetic Force Microscopy imaging, which reveals specific magnetic domain structures in the grains of different crystallographic orientations. It is found that in the HEA polycrystal, an increase of the applied magnetic field affects the formation of magnetic domains and leads to a transition from a labyrinth-like pattern to a dotted domain configuration, which is expressed differently in the differently oriented grains.

• Mikheenko, Pavlo (2022). Ideal diamagnetism in brain microtubules. Fulltekst i vitenarkiv Vis sammendrag

  With mounting evidences of superconductivity in brain microtubules, a key experiment to support its existence would be a nanometer-scale mapping of microtubule magnetic properties. Magnetic force microscopy is a convenient instrument to perform such mapping. Previously, it has been used qualitatively resulting in the detection of strong diamagnetic response coming from the in-plane bundles of microtubules. This was preliminary associated with the feature of ideal diamagnetism and therefore superconductivity in the microtubules. Numerical arguments, however, were absent and it was unclear in what substance superconductivity resides. In order to clarify this, magnetic force microscopy was extended to force spectroscopy, which records magnetic signal as a function of distance from the surface. Moreover, the magnetic force microscopy was performed on cross-sections of microtubules investigating them individually. In order to do this, a special technique of sample preparation has been developed allowing orienting microtubules perpendicular to the substrate. The magnetic mapping revealed strong diamagnetism coming from the inside of microtubules. The analysis of recorded force spectroscopy curves has been performed analytically separating magnetic and van der Waals contributions to the signal. Following this, estimation of the signal expected for ideal diamagnetism has been obtained and compared with the signal coming from the microtubules. It is concluded that microtubules display the property of ideal diamagnetism. The substance, in which superconductivity develops, is likely to be the structured water.

• Mikheenko, Pavlo; Jacquemin, M; Mojarrad, Masih & Mercier, Frederic (2022). Controlling dendritic flux avalanches by nanostructure of superconducting films. Fulltekst i vitenarkiv Vis sammendrag

  Niobium Nitrate (NbN) superconducting films are extensively used in superconducting electronics, for example as basic element of single-photon microwave resonators. Here we report on direct visualisation of magnetic flux penetration into a NbN thin film deposited by High-Temperature Chemical Vacuum Deposition (HTCVD). The film is of the thickness of 90.8 nm. It is deposited at temperature of 1200 C on a single-crystal α-Al2O3 (0001) c-axis substrate (sapphire). The visualisation is done by Magneto-Optical imaging allowing to see directly distribution of magnetic flux in the superconductor. It is found that at low temperatures magnetic flux penetrates into the film in the form of dendritic flux avalanches. Moreover, the shape of dendritic avalanches appeared to be very unusual, previously not reported in the literature. The branches of avalanches persistently follow one specific direction in the plane of the film. To clarify the origin of this effect, high-resolution Scanning Electron Microscopy and Atomic Force Microscopy have been used in combination with the Fast Fourier Transform of the obtained images. It was found that the origin of the selected direction in the dendritic flux penetration is deep on the nanometre scale, namely in nano-channels formed by the merging NbN crystallites during their growth. In this way, nanostructure of the film directly controls dendritic flux avalanches in the superconductor. Varying conditions of deposition would allow actively changing superconducting properties of the films.

• Mojarrad, Masih & Mikheenko, Pavlo (2022). Liquid Hydrogen and Use of Superconductors – a synergy. Fulltekst i vitenarkiv Vis sammendrag

  Nowadays, sustainable energies become more and more important to eliminate carbon-emission fuels. Hydrogen is one of the most desirable options since water is the only by-product of hydrogen consumption, and it has the highest specific energy (142 MJ/ kg) among all fuels. In contrast, hydrogen has a low volumetric energy density. To compensate for this problem, it is possible to provide hydrogen in liquid form. The boiling point of hydrogen is too low being 20 K (-253 ℃), therefore many might believe that it is a barrier to using it in industry. On the contrary, the low temperature of liquid hydrogen allows one to introduce superconductivity to the hydrogen industry. Superconductivity is the phenomenon of the resistivity-free feature of some materials for passing electricity. Superconductors are only operated at very low temperatures, but hopefully, some superconductors' critical temperature is above the boiling point of liquid hydrogen. This means that liquid hydrogen could be used as a coolant for the superconductors before it is implemented as a fuel. Superconductors lead to using less amount of energy due to their high efficiency and, consequently, have an abatement cost in the energy sector. The maritime industry in Norway aims to design vessels operating with liquid hydrogen, thus it might be the best time to use superconductors to make both technology more economic and efficient.

• Mikheenko, Pavlo (2022). Superconductivity in living organisms. Fulltekst i vitenarkiv Vis sammendrag

  Superconductivity in living organisms, specifically in central nervous system and brain, was suggested as early as in 1972 by E. Halperin and A. Wolf [1]. Even before that, in 1964, W. Little developed theoretical model for room-temperature superconductivity (RTS) in organic chains of molecules linked to specific molecular complexes, which could be present in living organisms [2]. The purpose of possible RTS was first not understood. Neither were experimental evidences present showing its existence. Situation changed when it became clear that superconductivity is efficient in quantum computing. Currently, functional superconductor-based quantum computers became reality. An opportunity appeared to explain extraordinary power of brain and nervous system. Experiments started too, first with crude electrical transport measurements of brain slices [3], then using more sophisticated nanometre-scale magnetic force microscopy [4]. The latter was intended to check ideal diamagnetism in brain nano-structures. A conclusion was made that superconductivity is likely to reside in microtubules: highly ordered quasi one-dimensional nanometre-size structures somewhat reminding those suggested by W. Little [2]. The estimate of critical temperature in brain tissue was made [3] and it was found to be close to that predicted by W. Little [2]. A concept of based-on-superconductivity quantum processing of information in living organisms was put forward [5]. In this work, new experimental evidences of RTS are given extending abilities of magnetic force microscopy to measuring cross-sections of microtubules. 1. E. H. Halperin and A. A. Wolf, Speculations of superconductivity in biological and organic systems. In: Advances in Cryogenic Engineering, vol. 17, Timmerhaus, K.D. (ed) Springer Science + Business Media LLC (1972). DOI: 10.1007/978-1-4684-7826-6. 2. W. A. Little, Possibility of synthesizing an organic superconductor, Phys. Rev. 134, A1416–A1424 (1964). 3. P. Mikheenko, Possible superconductivity in the brain, J. Supercond. Novel Magn., vol. 32, pp. 1121–1134, (2019). 4. P. Mikheenko, Magnetic Force Microscopy of Brain Microtubules, IEEE 11th Int. Conf. Nanomaterials: Applications & Properties, Sumy, Ukraine, 2021, pp. SNMS02-1 - SNMS02-4, DOI: 10.1109/NAP51885.2021.9568538. 5. P. Mikheenko, Nano Superconductivity and Quantum Processing of Information in Living Organisms, IEEE 10th Int. Conf. Nanom.: App. & Prop., Sumy, Ukraine, 2020, pp. 02SNS02-1-02SNS02-4, DOI:10.1109/NAP51477.2020.9309703.

• Perilla, Ana Lucia Campana; Joudeh, Nadeem; Merroun, Mohamed; Gomez-Bolivar, Jamie; Røyne, Anja & Linke, Dirk [Vis alle 7 forfattere av denne artikkelen] (2022). Biosynthesis and characterization of Palladium-Based Nanoparticles using Escherichia coli. Fulltekst i vitenarkiv
• Bazioti, Kalliopi; Poulia, Anthoula; Løvvik, Ole Martin; Azar, Amin S.; Mikheenko, Pavlo & Diplas, Spyridon [Vis alle 7 forfattere av denne artikkelen] (2021). Advanced Scanning Transmission Electron Microscopy investigations of FeCoNi(AlMn)x high-entropy alloy: nanoscale structure and impact on magnetic properties. Fulltekst i vitenarkiv
• Bazioti, Kalliopi; Poulia, Anthoula; Løvvik, Ole Martin; Carvalho, Patricia Almeida; Azar, Amin S. & Mikheenko, Pavlo [Vis alle 8 forfattere av denne artikkelen] (2021). STEM-EELS investigations and Lorentz microscopy unravelling the structural evolution of FeCoNi(AlMn)x high-entropy alloy and its impact on magnetic properties. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2021). Magnetic Force Microscopy of Brain Microtubules. Fulltekst i vitenarkiv
• Mojarrad, Masih; Hamid, Jouan; Perilla, Ana Lucia Campana; Dang, V.S.; Crisan, A. & Mikheenko, Pavlo (2021). Using magnetic nanoparticles to improve flux pinning in YBa2Cu3Ox films. Fulltekst i vitenarkiv
• Perilla, Ana Lucia Campana; Joudeh, Nadeem; Linke, Dirk & Mikheenko, Pavlo (2021). Magnetic decoration of Escherichia coli loaded with Palladium nanoparticles. Fulltekst i vitenarkiv
• Larsen, Aleksander; Poulia, Anthoula; Azar, Amin S.; Bazioti, Kalliopi; Carvalho, Patricia Almeida & Gunnæs, Anette Eleonora [Vis alle 9 forfattere av denne artikkelen] (2021). Identifying Magnetic Phases in Additively Manufactured High-Entropy Alloy FeCoNiAlxMnx. Fulltekst i vitenarkiv
• Poulia, Anthoula; Azar, Amin S.; Gunnæs, Anette Eleonora; Bazioti, Kalliopi; Mikheenko, Pavlo & Diplas, Spyridon (2021). Tailoring mechanical and magnetic properties of the FeCoNi(AlMn)x high entropy alloys via compositional alterations. Fulltekst i vitenarkiv
• Poulia, Anthoula; Azar, Amin S.; Bazioti, Kalliopi; Gunnæs, Anette Eleonora; Mikheenko, Pavlo & Diplas, Spyridon (2021). Additively manufactured FeCoNi(AlMn)x high entropy alloys: Mechanical and magnetic properties investigation. Fulltekst i vitenarkiv
• Poulia, Anthoula; Azar, Amin S.; Bazioti, Kalliopi; Gunnæs, Anette Eleonora; Mikheenko, Pavlo & Diplas, Spyridon (2021). Investigation of High Entropy Alloys via Magnetic Force Microscopy. Fulltekst i vitenarkiv
• Bazioti, Kalliopi; Poulia, Anthoula; Løvvik, Ole Martin; Azar, Amin S.; Mikheenko, Pavlo & Diplas, Spyridon [Vis alle 7 forfattere av denne artikkelen] (2021). Structural evolution of FeCoNi(AlMn)x high-entropy alloy and impact on magnetic properties: nano-scale STEM-EELS investigations. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2020). Magnetic characterization of palladium nanoparticles. Fulltekst i vitenarkiv
• Perilla, Ana Lucia Campaña; Joudeh, Nadeem; Høyer, Henrik; Røyne, Anja; Linke, Dirk & Mikheenko, Pavlo (2020). Probing van der Waals and magnetic forces in bacteria with magnetic nanoparticles. Fulltekst i vitenarkiv Vis sammendrag

  Bioinspired metal-based nanoparticles have potential uses in many applications, but before a possible commercial exploitation, it is important to clarify the pathways of their production and deposition inside the organisms, for example in bacteria. The technique of magnetic force microscopy (MFM) could be used to evaluate the nanoparticles magnetic properties, in addition to allowing tracing their location inside or outside of bacteria, which could help to understand pathways of their biosynthesis. In this work, using MFM and analyzing the interaction of magnetic tip with nanoparticles and bacteria imbedded in resin at different heights above the surface, and comparing gradients of forces recorded by magnetic and non-magnetic tips, a condition was found, which allows to measure pure magnetic response of Pd-Fe nanoparticles. For these nanoparticles, the interplay between magnetic and van der Waals forces is described at small distances to the surface. Experimental data are compared with simulations, based on the calculation of the distribution of magnetic field around a nanoparticle, which defines magnetic force acting on the MFM tip.

• Poulia, Anthoula; Azar, Amin S.; Svec, Peter; Bazioti, Kalliopi; Belle, Branson & Gunnæs, Anette Eleonora [Vis alle 8 forfattere av denne artikkelen] (2020). Nanoscale Magnetic Properties of Additively Manufactured FeCoNiAlxMnx High-Entropy Alloys. Fulltekst i vitenarkiv Vis sammendrag

  Magnetic properties of High-Entropy Alloys based on the Fe-Co-Ni-Al-Mn system are reported. High-Entropy Alloys are cutting-edge technological materials containing five or more elements in relatively high concentrations (5–35 at.%) within one or several solid-state solutions. These solutions are stabilized at the nanometer scale due to the high contribution of the mixing entropy to the Gibbs free energy, which can overcome the enthalpic contribution. Two magnetic alloys are found in FeCoNiAlxMnx (1.6 at.%  x  7.8 at.%) samples processed by laser metal deposition. The magnetic techniques used to screen the materials were magneto-optical imaging and magnetic force microscopy. The former allows characterizing magnetic properties within the mm-μm scale, while the latter is efficient down to the nanometer scale. Magnetic screening confirms the importance of the nanostructure in defining magnetic properties of the alloys, and the trends in the magnetic behavior as a function of the alloy composition are revealed. The experimental results suggest that it is possible to form unique alloys, which may outperform conventional magnetic materials used in a variety of applications such as transformers, screening shields and wind power generators.

• Mikheenko, Pavlo (2020). Nano superconductivity and quantum processing of information in living organisms. Fulltekst i vitenarkiv Vis sammendrag

  With the advance of superconducting quantum computing and the attempts of extending its operating range to higher temperatures, a special attention is paid to nanostructured quantum circuits. In particular, quasi one-dimensional quantum wires with phase slip centers are argued to be promising structures for the next generation of quantum computers. In its turn, this stimulates revisiting the question about the possibility of quantum processing of information in quasi one-dimensional structures in the nervous system, specifically the brain, in living organisms, especially in the light of recent findings that suggest robust room-temperature superconductivity in these structures. The early theories of superconductivity were in favor of its quasi one-dimensional nature, and the recent findings suggest that reducing dimensions of a system could be a good approach for increasing the critical temperature of a material. Here, based on experimental data, it is argued that both room-temperature superconductivity and quantum processing of information are possible in the microtubules that are abundant in the nervous system and form the scaffolding of every cell in advanced living organisms. The origin of superconductivity in microtubules, and the way in which quantum processing of information may take place in them, are discussed. The role of Josephson oscillations in processing and exchange of information is emphasized.

• Claxton, James; Joudeh, Nadeem; Røyne, Anja; Linke, Dirk & Mikheenko, Pavlo (2020). Sequential magnetic mapping of bacteria loaded with Pd-Fe nanoparticles. Fulltekst i vitenarkiv Vis sammendrag

  Magnetic nanoparticles are of widespread use in nanotechnology. One of the most unusual are magnetic palladium nanoparticles that combine magnetism with high catalytic activity. These nanoparticles could be obtained biologically by exposing bacteria to a palladium salt. Due to their small size and weak magnetism, however, it is challenging to measure their magnetic properties. One of the solutions to enhance their magnetism is to incorporate a small amount of iron atoms into them. After this procedure, the nanoparticles together with bacteria can be embedded in resin and characterized by the technique of magnetic force microscopy. This technique allows imaging cross-sections of the bacteria with nanoparticles, but cannot give information from the depth of the sample. Here we report on an approach partially solving this problem. Its novelty lies in measurements of consecutive thin slices of resin, which allows mapping cross-sections of individual bacteria and different parts of the material surrounding the same bacterium. An interesting observed feature is the formation of magnetic chains of nanoparticles outside of the bacteria.

• Mikheenko, Pavlo (2019). Low-dimensional superconductivity: a road to higher critical temperature. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2019). Making invisible visible on the nanometre scale: seeing magnetism of palladium nanoparticles. [Internet]. https://digitallifenorway.org/blogg. Fulltekst i vitenarkiv
• Mikheenko, Pavlo; Baba, Elbruz Murat & Karazhanov, Smagul (2019). Electrical and Magnetic Behavior of GdOH Thin Films: a Search for Hydrogen Anion Superconductivity. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2019). Dislocations as Origin of High Critical Current Density in Bulk MgB2. Fulltekst i vitenarkiv
• Joudeh, Nadeem; Røyne, Anja; Mikheenko, Pavlo & Linke, Dirk (2019). Bio-Engineered Palladium Nanoparticles (BEDPAN). Fulltekst i vitenarkiv
• Mikheenko, Pavlo; Mikheenko, Iryna; Joudeh, Nadeem; Claxton, J. B.; Røyne, Anja & Linke, Dirk (2019). Imaging magnetism of biologically produced palladium nanoparticles. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2019). Nanotubular superconductivity and quantum processing of information in brain. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2019). Superconductivity and quantum processing of information in brain: fact or fantasy? Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2019). A search for room temperature superconductivity. Fulltekst i vitenarkiv Vis sammendrag

  There is impressive progress in increasing critical temperature (Tc) of superconducting compounds. With the recent discovery of superconductivity at high pressure in H3S with Tc of 203 K [1], the prospects of finding room temperature superconductivity become quite realistic. The important pathways for synthesis of compounds with high Tc were outlined in [2]. The conclusion of the paper is that the highest probability of discovering room temperature superconductivity is in hydrated, to which H3S belongs too. The specifics of hydrates is that pairing interaction is provided by high-energy optical, in addition to acoustic, phonons [3]. Presence of light elements like hydrogen is crucial for high Tc. Another way to reach Tc above room temperature is to use electron-electron rather than electron-phonon pairing interaction. This was demonstrated by Little in his theoretical model [4]. Additional to employing electron-electron interaction, important assumption of [4] is to use a low-dimensional quantum system. Early search for new superconductors in three-dimensional (3D) materials did not give particular high Tc until a quasi-2D class of materials was discovered by Bednorz and Mueller [5]. Quasi-1D organic systems with specific pairing interaction [4] promise much higher Tc, up to 2200 K. Knowing this tendency and following general idea suggested in [6] that if room-temperature superconductivity exists, it should be in a system with high level of organization, i.e. nervous system and brain, electrical measurements of brain slices were performed [7]. In these measurements, the idea to use graphene as room-temperature quantum mediator was utilized [8]. The brain is composed of neurons containing microtubules, which are quasi-1D organic structures that might be responsible for superconductivity. The results of electrical measurements of brain slices will be reported. The estimated from the measurements Tc is close to that predicted in the model of Little [4]. 1. Drozdov, A. P., Eremets, M. I., Troyan, I. A., Ksenofontov, V., Shylin, S. I.: Nature 525, 73 (2015). 2. Kresin, V.Z.: J. of Supercond. and Novel Magn. 31, 611 (2018). 3. Gor’kov, L. P., Kresin, V.Z.: Rev. Mod. Phys. 90, 011001 (2018). 4. Little, W. A.: Phys. Rev. 134, A1416 (1964). 5. Bednorz, G., and Mueller, K.: Z. Phys. B 64, 189 (1986). 6. Halperin, E.H., Wolf, A.A.: Speculations of superconductivity in biological and organic systems. In: Advances in cryogenic engineering, vol. 17, Timmerhaus, K.D. (ed) Springer Science + Business Media LLC (1972). 7. Mikheenko, P.: J. of Supercond. and Novel Magn., submitted (2018). 8. Mikheenko, P.: IEEE Xplore Digital Library 7757272 (2016).

• Hjelmeland, Trude Bjørgås; Volkov, Y & Mikheenko, Pavlo (2018). Spin injection from La0.67Ca0.33MnO3 into superconducting thin film of YBa2Cu3O7-x. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2018). Possible high-temperature superconductivity in brain. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2018). Are any hopes to have room-temperature superconductivity? Fulltekst i vitenarkiv
• Qureishy, Thomas; Laliena, Carlos; Martínez, Elena; Qviller, Atle Jorstad; Vestgården, Jørn Inge & Johansen, Tom Henning [Vis alle 8 forfattere av denne artikkelen] (2018). Magneto-optical imaging of dendritic flux avalanches in a superconducting MgB2 tape. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2017). Magnetic flux avalanches in superconductors. Fulltekst i vitenarkiv
• Fjellvåg, Asbjørn Slagtern; Hjelmeland, Trude; Mollatt, Hans Jakob; Qureishy, Thomas & Mikheenko, Pavlo (2017). Interplay between spin polarization and superconductivity in an ex-situ bilayer La0.67Ca0.33MnO3 - YBa2Cu3O7-x. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2017). Nano materials for renewable energy economy. Fulltekst i vitenarkiv
• Mikheenko, Pavlo; Qureishy, Thomas; Mercier, Frederic; Jacquemin, M & Pons, M (2017). Dendritic flux avalanches in high-quality NbN superconducting films. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2017). Critical phenomena in superconductors: dendritic flux instabilities against Bean critical state. Fulltekst i vitenarkiv
• Mikheenko, Pavlo (2017). Introduction to superconductivity. Fulltekst i vitenarkiv
• Perilla, Ana Lucia Campana; Linke, Dirk; Mikheenko, Pavlo & Røyne, Anja (2024). Palladium-based nanoparticles produced by Escherichia coli: Insights into synthesis and physicochemical characterization of microbial nanoparticles. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Microorganisms such as bacteria can produce a wide range of metallic nanoparticles, including the highly versatile palladium nanoparticles (Pd NPs). Current industrial methods for NP production often require large amounts of energy, use toxic chemicals, and generate waste. Microbial processes offer a green alternative for NP production, and the possibility to engineer these processes using genetic tools. Pd NPs are invaluable tools across numerous exciting applications in medicine, engineering, electronics, and chemistry. Understanding and controlling the synthesis of Pd NPs is crucial as their magnetic and catalytic properties are strongly dependent on their size, shape, and on the presence of other metals such as iron (Fe) that could enhance their performance even further. Surprisingly, little is known about the production of Pd-Fe nanoparticles by bacteria, despite their promising uses. In this thesis, we employed various advanced techniques to characterize Pd and Pd-Fe NPs produced by Escherichia coli bacteria, uncovering valuable insights into their composition, size, localization, and catalytic activity. These results will enable the use of bacterial Pd-Fe NPs as efficient and sustainable catalysts for applications like wastewater treatment and fine chemical synthesis in the future. Additionally, our novel methodology for studying the magnetism of Pd-based NPs directly within bacterial cells opens doors for exciting future research.

• Joudeh, Nadeem; Linke, Dirk & Mikheenko, Pavlo (2022). Escherichia coli-mediated palladium nanoparticle synthesis. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Palladium nanoparticles (Pd NPs) offer a wide range of novel and exciting applications in catalysis, medicine, engineering, and electronics. Currently, these NPs are synthesized using conventional physical and chemical methods. These methods have several disadvantages as the physical methods usually require energy-intensive processes, and the chemical methods often involve harmful solvents or produce toxic by-products. Lately, more environmentally friendly approaches for the synthesis of NPs have emerged using microorganisms. Several bacteria were reported for their ability to biosynthesize Pd NPs. In this process, Pd ions are biologically transported into the bacterial cells and subsequently reduced to metallic Pd, forming Pd NPs. The current knowledge on the proteins, enzymes, or pathways involved in the transport and reduction of Pd is very limited, which hinders the ability to genetically engineer bacterial strains capable of producing Pd NPs with fine-tuned properties. This thesis provides new insights on the genes that might be responsible for the transport of Pd ions in E. coli, the toxicological effects of Pd, and the potential detoxification strategies that E. coli employ to deal with Pd stress. In addition, this thesis describes an E. coli-mediated approach for the synthesis of 1-2 nm Pd and Pd-Fe NPs displaying novel ferromagnetic properties. At the same time, this thesis shows different methods for the characterization of the magnetic properties of these NPs in biological samples.

• Berg, Amalie; Haug, Halvard & Mikheenko, Pavlo (2019). Temperature and injection dependent photoluminescence imaging of charge carrier lifetime in multicrystalline silicon wafers. Universitetet i Oslo. Fulltekst i vitenarkiv

Se alle arbeider i NVA