2002/11/27 by I. V. Solovyev · 4 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Antiferromagnetism #Chemical and Physical Properties of Materials #Coulomb #Electronic structure #Fermi level #Ferromagnetism #Magnetic structure #Magnetization #Nuclear materials and radiation effects #Pyrochlore #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.67.174406
published as Phys. Rev. B 67, 174406 (2003) · 26 pages, 17 figures (low resolution is used for Figs. 6, 8, and 9, please contact directly if you need the originals), 1 table
arxiv created 2002/11/27 · openalex publication_date 2003/05/12 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Being motivated by recent experimental studies, we investigate magnetic structures of the Mo pyrochlores A2Mo2O7 (A=Y, Nd, and Gd) and their impact on the electronic properties. The latter are closely related with the behavior of twelve Mo(t2g) bands, located near the Fermi level and well separated from the rest of the spectrum. We use a mean-field Hartree-Fock approach, which combines fine details of the electronic structure for these bands, extracted from the conventional calculations in the local-density approximation, the spin-orbit interaction, and the on-site Coulomb interactions among the Mo(4d) electrons, treated in the most general rotationally invariant form. The Coulomb repulsion U plays a very important role in the problem, and the semi-empirical value U\ensuremath∼1.5--2.5eV accounts simultaneously for the metal-insulator (MI) transition, the ferromagnetic (FM)---spin-glass (SG) transition, and for the observed enhancement of the anomalous Hall effect (AHE). The MI transition is mainly controlled by U. The magnetic structure at the metallic side is nearly collinear FM, due to the double exchange mechanism. The transition into the insulating state is accompanied by the large canting of spin and orbital magnetic moments. The sign of exchange interactions in the insulating state is controlled by the Mo-Mo distances. Smaller distances favor the antiferromagnetic coupling, which predetermines the SG behavior in the frustrated pyrochlore lattice. A large AHE is expected in the nearly collinear FM state, near the point of MI transition, and is related with the unquenched orbital magnetization at the Mo sites. We also predict a large magneto-optical effect in the same FM compounds.