Understanding the temperature- and pressure-dependent electronic properties of FeSi: DFT + DMFT study

Abstract

Electronic structures of FeSi and Fe1.02Si0.98 under pressure (achieved through volume compression) have been investigated by using DFT+DMFT and KKR-CPA methods, respectively. The widening of band gap with increasing pressure suggests that the experimentally observed insulator-to-metal transition temperature should shift towards the higher temperature for FeSi. KKR-CPA calculations have shown the presence of impurity states in the gapped region which predicts the half-metallic nature. The closure of the gap (in one spin channel) with pressure increment appears to be responsible for the experimentally observed semiconductor-to-metal transition in Fe excess samples at a temperature below 50 K. Magnetic moments at Fe excess sites are found to be decreasing with increasing pressure from per Fe atom () to per Fe atom (). Moreover, for FeSi the calculated local spin susceptibility has shown decreasing behavior with pressure rise similar to experimental result.