1998/04/30 by Tsutomu Momoi, Kenn Kubo · 4 citations
Physics and Astronomy · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.58.r567
published as Phys. Rev. B 58, R567 (1998) · 4 pages, Revtex, 3 figures, corrected some typos and references, to be published in Phys. Rev. B (Rapid Communication)
arxiv created 1998/06/15 · openalex publication_date 1998/07/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study the ferromagnetism due to orbital degeneracy in the Hubbard model in infinite dimensions. The model contains the intraorbital repulsion U, the interorbital repulsion U^\ensuremath', the exchange J (Hund coupling) and the pair hopping J^\ensuremath', where all of them originate from the on-site Coulomb interaction. The ground state of the effective one-site problem was obtained by exact diagonalizations of finite clusters. At the (1)/(4) filling, we found two insulating phases; one is a ferromagnetic phase with alternating orbital order and the other is antiferromagnetic with uniform orbital order. If electrons are doped into the (1)/(4) filling, the ferromagnetic phase still survives and becomes metallic, while the antiferromagnetic phase disappears. This result indicates that a double-exchange mechanism is relevant to stabilize metallic ferromagnetism in infinite dimensions.