Hidden T -square resistivity regime in FeSe

AMIGÓ, M. L.; G. NIEVA; FACIO, JORGE I.

Workshop; Bariloche Workshop on condensed matter physics; 2023

We investigate the electronic transport properties in the tetragonal phase of FeSe for temperatures up to 400 K. The salient features of the high-temperature resistivity are the presence of maxima as a function of temperature which happen in the ab-plane at T max,ab =297(3) K and along the c axis at T max,c =228(3) K. We argue that the smallness of the Fermi surfaces in FeSe plays a role in a number of points which are relevant for the high-temperature data. Particularly, we discuss our observations in connection to photoemission experiments that have analyzed the temperature evolution of the electronic structure in the tetragonal phase. To this aim, we consider a tight-binding Hamiltonian that accurately reproduce photoemission results at T =100 K, which has been previously shown to predict a strong change of the chemical potential as a function of temperature, of the order of the Fermi energy itself. We show that such a shift should yield a strong enhancementof the carrier density which is, however, insufficient to explain the resistivity maxima. We point out one mechanism based on temperature-dependent shifts of the band structure, other than the change of the chemical potential, that can contribute to the resistivity decrease at large temperature.