2010/07/14 by P. Piekarz, Przemysław Piekarz, Andrzej M. Oleś +6
Engineering · Materials Science · Physics and Astronomy · #FOS: Physical sciences #Magnetic Properties and Synthesis of Ferrites #Microstructure and Mechanical Properties of Steels #Strongly Correlated Electrons (cond-mat.str-el) #X-ray Diffraction in Crystallography #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.1007.2340
6 pages, 6 figures
arxiv created 2010/07/14 · openalex publication_date 2010/07/14 · arxiv updated 2010/07/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The electronic properties of two spinels Fe3O4 and Fe2SiO4 are studied by the density functional theory. The local Coulomb repulsion U and the Hund's exchange J between the 3d electrons on iron are included. For U=0, both spinels are half-metals, with the minority t2g states at the Fermi level. Magnetite remains a metal in a cubic phase even at large values of U. The metal-insulator transition is induced by the X3 phonon, which lowers the total energy and stabilizes the charge-orbital ordering. Fe2SiO4 transforms to a Mott insulating state for U>2 eV with a gap Δg∼ U. The antiferromagnetic interactions induce the tetragonal distortion, which releases the geometrical frustration and stabilizes the long-range order. The differences of electronic structures in the high-symmetry cubic phases and the distorted low-symmetry phases of both spinels are discussed.