Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 36: Materials and Devices for Quantum Technology II
HL 36.8: Vortrag
Mittwoch, 19. März 2025, 17:00–17:15, H13
Signature of topological transitions in Na-Sb-Bi alloys via Compton scattering — •Aki Pulkkinen1, Veenavee Kothalawala2, Kosuke Suzuki3, Bernardo Barbiellini2,4,5, Hiroshi Sakurai3, Ján Minár1, and Arun Bansil4,5 — 1New Technologies-Research Centre, Pilsen, Czech Republic — 2School of Engineering Science, LUT University, Finland — 3Graduate School of Science and Technology, Gunma University, Japan — 4Department of Physics, Northeastern University, USA — 5Quantum Materials and Sensing Institute, Northeastern University, USA
We investigate the topological transition in Na-Sb-Bi alloys using x-ray Compton scattering experiments, combined with first-principles modeling of the electronic structure. A robust signature of the semiconductor-to-Dirac semimetal transition is identified in the spherically averaged Compton profile. We demonstrate the evolution of the electronic structure across the topological transition as a function of Bi concentration using the coherent potential approximation (CPA) within the fully relativistic, full potential Korringa-Kohn-Rostoker (KKR) method implemented in the SPRKKR package. Spherically averaged Compton profiles are estimated by averaging over directional profiles over a set of special directions within the KKR method. We demonstrate how the number of electrons involved in the topological transition can be estimated, providing a new descriptor to quantify the strength of the spin-orbit coupling driving the transition. Our study also highlights the sensitivity of the Compton scattering technique in capturing the spillover of Bi 6p relativistic states onto Na sites.
Keywords: Compton scattering; Electronic structure; Topological transition; Coherent potential approximation