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

[摘要] Recent studies of FeSi(1-x)Gex, 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)Gex for different x and different volumes for large x. The results show that the small band gap in FeSi is closed for x greater than or equal to 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. (C) 2004 Elsevier B.V. All rights reserved.

[发布日期] 2004-12-01

[关键词] electronic structure;metal-insulator transition;disorder;magnetism;Fe-alloys