Fizika Nizkikh Temperatur: Volume 45, Number 11 (November 2019), p. 1381-1386    ( to contents , go back )

Temperature induced shift of electronic band structure in Fe(Se,Te)

Yu.V. Pustovit and A.A. Kordyuk

Kyiv Academic University, Kyiv 03142, Ukraine
Institute of Metal Physics of National Academy of Sciences of Ukraine, Kyiv 03142, Ukraine
E-mail: kordyuk@gmail.com

Received March 14, 2019, published online September 26, 2019

Abstract

FeSe, the simplest iron-based superconductor, reveals a variety of puzzling properties and features that could hold a key for the pairing mechanism in this family of superconductors. In particular, it’s complex electronic band structure differs essentially from the DFT calculated one in a specially way called the “red-blue shift” and, in addition, drifts anomalously with temperature. Here we study this band structure evolution in Fe(Se,Te) crystals and reveal essential downdrift of all the hole-like bands with increasing temperature, which is opposite to the “red-blue shift” expectation. We show that this drift cannot be described by temperature-dependent contribution to quasiparticle self-energy within the Fermi-liquid concept but could result in charge redistribution between the bulk and topological surface states. If such a scenario is confirmed, one can tune the topologically non-trivial bands near the Fermi level with temperature, potentially allowing temperature-induced crossover between differ-ent Fermi surface topologies.

Key words: electronic band structure, Fermi level, pnictides, chalcogenides.

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