Metal-insulator transition in TlSr{sub 2}CoO{sub 5} from orbital degeneracy and spin disproportionation

Journal Article · Wed Aug 15 04:00:00 EDT 2001 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.64.075104· OSTI ID:40230847

Foerster, D; Hayn, R; Pruschke, T; Zoelfl, M; Rosner, H

To describe the metal-insulator transition in the oxide TlSr{sub 2}CoO{sub 5}, we investigate the electronic structure of its high-temperature tetragonal phase by the local density approximation (LDA) and model Hartree-Fock calculations. Within the LDA we find a homogeneous metallic and ferromagnetic ground state; however, when including the strong Coulomb interaction in the 3d shell more explicitly within the Hartree-Fock approximation, we find an insulating state of lower energy that exhibits both spin and orbital order. The instability of the metallic state toward the insulating one is driven by orbital degeneracy and a near degeneracy in energy of states of intermediate (s=1) and high (s=2) spin. We also interpret our results in terms of a simple model.

• Sponsoring Organization: (US)
• OSTI ID: 40230847
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 7 Vol. 64; ISSN 0163-1829
• Publisher: The American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTRONIC STRUCTURE
GROUND STATES
INSTABILITY
OXIDATION
OXIDES
REDUCTION
SPIN