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Exchange gap in GdPtBi probed by magneto-optics

Publication at Faculty of Mathematics and Physics |
2023

Abstract

We measured the magneto-reflectivity spectra (4-90 meV, 0-16 T) of the triple-point semimetal GdPtBi and found them to demonstrate two unusual broad features emerging in field. The electronic bands of GdPtBi are expected to experience large exchange-mediated shifts, which lends itself to a description via effective Zeeman splittings with a large g factor.

Based on this approach, along with an ab initio band structure analysis, we propose a model Hamiltonian that describes our observations well and allows us to estimate the effective g factor, g* = 95. We conclude that we directly observe the exchange-induced gamma(8) band inversion in GdPtBi by means of infrared spectroscopy.