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arXiv · 2506.02833

Probing the semiconductor-to-dirac semimetal transition in Na-Sb-Bi alloys with x-ray Compton scattering

Aki Pulkkinen·Veenavee Nipunika Kothalawala·Kosuke Suzuki·Bernardo Barbiellini·Johannes Nokelainen·Wei-Chi Chiu·Bahadur Singh·Hsin Lin·Alok K. Pandey·Naoaki Yabuuchi·Naruki Tsuji·Yoshiharu Sakurai·Hiroshi Sakurai·Ján Minár·Arun Bansil
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Abstract

We discuss electron redistribution during the semiconductor-to-Dirac semimetal transition in Na-Sb-Bi alloys using x-ray Compton scattering experiments combined with first-principles electronic structure modeling. A robust signature of the semiconductor-to-Dirac semimetal transition is identified in the spherically averaged Compton profile. We demonstrate how the number of electrons involved in this transition can be estimated to provide a novel descriptor for quantifying the strength of spin-orbit coupling responsible for driving the transition. The associated theoretical deviation of the Born charge of Na in Na$_3$Bi from the expected ionic charge of +1 is found to be consistent with the corresponding experimental value of about 10%. Our study also shows the sensitivity of the Compton scattering technique toward capturing the spillover of Bi 6p relativistic states onto Na sites.

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Aki Pulkkinen, Veenavee Nipunika Kothalawala, Kosuke Suzuki, Bernardo Barbiellini, Johannes Nokelainen, Wei-Chi Chiu, Bahadur Singh, Hsin Lin, Alok K. Pandey, Naoaki Yabuuchi, Naruki Tsuji, Yoshiharu Sakurai, Hiroshi Sakurai, Ján Minár, Arun Bansil. 2025-06-03. Probing the semiconductor-to-dirac semimetal transition in Na-Sb-Bi alloys with x-ray Compton scattering. https://doi.org/10.1103/nwrs-tmf2

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