Richard Justin Schenk

• Andreassen, Magnus; Rosnes, Andreas; Petersen, Clemens; Schenk, Richard Justin; Both, Kevin Gregor & Bergum, Kristin [Vis alle 7 forfattere av denne artikkelen] (2026). Combinatorial Synthesis and Characterization of Lattice-Matched Ga2O3–Cr2O3 and Ga2O3–V2O3 Sesquioxide Alloys for Ultrawide-Bandgap Semiconductor Applications. Physica Status Solidi (a) applications and materials science. ISSN 1862-6300. 223(15). doi: 10.1002/pssa.70437. Fulltekst i vitenarkiv Vis sammendrag

  Gallium sesquioxide is a wide‐bandgap semiconductor of high interest for power electronics and deep UV‐sensing applications. The α‐phase ( E g  = 5.6 eV) can be synthesized with excellent crystal quality on isostructural Al 2 O 3 substrates, removing the need for expensive homoepitaxial growth that is required for the thermodynamically stable β‐phase ( E g  = 4.9 eV). Here, continuous composition spread material libraries of (Ga 1‐ x V x ) 2 O 3 and (Ga 1‐ x Cr x ) 2 O 3 with 0.05 <  x  < 0.45 are synthesized by pulsed laser deposition, and characterized structurally and optically with the aim of decreasing the optical absorption edge of α‐Ga 2 O 3 to expand the range of potential optoelectronic applications. The (Cr x Ga 1‐ x ) 2 O 3 material library remained stable in the rhombohedral α‐phase throughout the investigated compositional range, exhibiting high crystal quality with minimal changes to the unit cell parameters. A systematic shift in optical absorption edge from 5.5 to 3.9 eV is observed, as determined by spectrophotometry. The (Ga 1‐ x V x ) 2 O 3 material library exhibits a systematic shift from 5.2 to 2.9 eV with increasing x V , but a region of decreased crystal quality is observed for 0.11 ≤  x V  ≤ 0.20. Additionally, a secondary V 2 O 5 phase is observed for x V  > 0.23. Overall, bandgap engineering of α‐(Ga 1‐ x V x ) 2 O 3 and α‐(Ga 1‐ x Cr x ) 2 O 3 is demonstrated, and chromium substitution is identified as especially promising due to high crystallinity and systematic change of optical absorption edge.

• Brinkman, Stefanie Suzanne; Tan, Xin Liang; Brekke, Bjørnulf; Mathisen, Anders Christian; Finnseth, Øyvind & Schenk, Richard Justin [Vis alle 18 forfattere av denne artikkelen] (2024). Chirality-Driven Orbital Angular Momentum and Circular Dichroism in CoSi. Physical Review Letters. ISSN 0031-9007. 132(19). doi: 10.1103/PhysRevLett.132.196402. Fulltekst i vitenarkiv Vis sammendrag

  Chiral crystals and molecules were recently predicted to form an intriguing platform for unconventional orbital physics. Here, we report the observation of chirality-driven orbital textures in the bulk electronic structure of CoSi, a prototype member of the cubic B20 family of chiral crystals. Using circular dichroism in soft x-ray angle-resolved photoemission, we demonstrate the formation of a bulk orbital-angular-momentum texture and monopolelike orbital-momentum locking that depends on crystal handedness. We introduce the intrinsic chiral circular dichroism, 𝑖�⁢𝑐�⁢CD, as a differential photoemission observable and a natural probe of chiral electron states. Our findings render chiral crystals promising for spin-orbitronics applications.

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• Schenk, Richard Justin; Skarpeid, Alv; Røst, Håkon; Yadav, Rohit; Cooil, Simon Phillip & Wells, Justin William (2026). Modifying the Electronic Structure of Nickel with Antimony Surface Alloys. Fulltekst i vitenarkiv
• Brinkman, Stefanie Suzanne; Tan, Xin Liang; Brekke, Bjørnulf; Mathisen, Anders Christian; Finnseth, Øyvind & Schenk, Richard Justin [Vis alle 7 forfattere av denne artikkelen] (2024). Chirality-Driven Orbital Angular Momentum and Circular Dichroism in CoSi. Fulltekst i vitenarkiv
• Schenk, Richard Justin; Mathisen, Anders Christian; Brinkman, Stefanie Suzanne; Tan, Xin Liang; Hartl, Matthias & Brüne, Christoph [Vis alle 7 forfattere av denne artikkelen] (2024). Growth and surface characterization of epitaxial CuFeS2 thin films on Si(001). Fulltekst i vitenarkiv
• Stalsberg, Marte Pedersen; Schenk, Richard Justin; Roberts, Daniel; Rørheim, Adrian Næraa; Moen-Duran, Oliver & Wells, Justin William [Vis alle 7 forfattere av denne artikkelen] (2024). Towards a p-n heterojunction of Ga2O3 and diamond. Fulltekst i vitenarkiv
• Schenk, Richard Justin; Bentmann, Hendrik & Brüne, Christoph (2024). Angle-resolved Photoelectron Spectroscopy of Epitaxial CuFeS2 Thin Films. Norges teknisk-naturvitenskapelige universitet. Fulltekst i vitenarkiv Vis sammendrag

  CuFeS2, colloquially known as chalcopyrite, is an antiferromagnet semiconductor with an exceptionally high Néel temperature of 823 K. Its close lattice match with silicon, the abundance of its constituents and the tunability of its electric properties through doping make this material a promising candidate for spintronic applications. Its magnetic space group (I-42d’) allows for antiferromagnetically-induced, wavevector-dependent spin-splitting of the electronic bands associated with altermagnetism. In this work, I establish the surface preparation of epitaxially grown CuFeS2(001) thin films by Ar+ sputtering and annealing. The surface composition is investigated by XPS as a function of the preparation. Using LEED, I determine that the surface structure corresponds to a zincblende lattice and not the expected chalcopyrite lattice. I further demonstrate soft X-ray ARPES and resonant photoemission across the Cu L3 and Fe L2,3 edges to gain insight into the valence band structure of the material. As in LEED, the reciprocal space periodicity found in ARPES closely resembles a zincblende lattice instead of a chalcopyrite lattice, and a poor match of the measurements with DFT-calculations is found. Resonant photoemission reveals that the band structure features observed in ARPES belong to previously unreported states in the valence band. Based on their resonant behaviour over the Fe L2,3 edges, I conclude that these states are likely derived from iron d-orbitals. In summary, this thesis lays the foundation for a deeper understanding of the chalcopyrite band structure. I highlight and discuss potential explanations for the appearance of a zincblende lattice and the discrepancy between the DFT-calculations and ARPES measurements.

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