Electronic structure and magnetism for FeSi$_{(1-x)}$Ge$_x$ from supercell calculations

T. Jarlborg

doi:10.1016/j.jmmm.2004.05.028

paper

Electronic structure and magnetism for FeSi $_{(1 - x)}$ Ge $_{x}$ from supercell calculations

arXiv:cond-mat/0404026 · doi:10.1016/j.jmmm.2004.05.028

Abstract

Recent studies of FeSi $_{(1 - x)}$ Ge $_{x}$ , which found a transition from an insulating to a magnetic metallic state near $x$ =0.25, have revived the discussion about the role of strong correlation in these systems. Here are spin polarized band calculations made for 64-atom supercells of FeSi $_{(1 - x)}$ Ge $_{x}$ for different $x$ and different volumes for large $x$ . The results show that the small band gap in FeSi is closed for $x \geq 0.3$ , because of both substitutional disorder and increased volume. Ferromagnetism appears near this composition and becomes enforced for increasing $x$ . The $x$ -dependence of the electronic specific heat can be understood from the exchange splitting of the density-of-states near the gap. Strong volume dependencies for the properties of FeGe suggest experiments using pressure instead of $x$ for investigations of the gap.

(7 pages, 4 figures)

Electronic structure and magnetism for FeSi(1−x)​Gex​ from supercell calculations

Abstract

Electronic structure and magnetism for FeSi $_{(1 - x)}$ Ge $_{x}$ from supercell calculations