Superconducting states in a two-orbital Hubbard model on a triangular lattice

Kenji Kobayashi; Hisatoshi Yokoyama

doi:10.1016/j.jmmm.2006.10.107

Superconducting states in a two-orbital Hubbard model on a triangular lattice

Kenji Kobayashi, Hisatoshi Yokoyama

SCI - Physics

Research output: Contribution to journal › Article › peer-review

Abstract

As a model of the novel superconductor Na_x CoO₂ · y H₂ O, we study a triangular Hubbard model with doubly degenerate atomic orbitals, using an optimization variational Monte Carlo method. It is found that when the isolated Fermi surface overlaps the van Hove singularity points, d_{x2 - y2} and d + i d-wave superconducting states, among various pairing symmetries, become stabilized by large Coulomb interactions. The pairing is originating from the interaction-energy gain induced dominantly by the enhancement of antiferromagnetic spin correlations. The possibility of triplet pairing is limited for the present parameterization.

Original language	English
Pages (from-to)	651-653
Number of pages	3
Journal	Journal of Magnetism and Magnetic Materials
Volume	310
Issue number	2 SUPPL. PART 1
DOIs	https://doi.org/10.1016/j.jmmm.2006.10.107
Publication status	Published - 2007 Mar 1

Keywords

Hubbard model
Pairing symmetries
Transition-metal oxides
Variational method

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

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abstract = "As a model of the novel superconductor Nax CoO2 · y H2 O, we study a triangular Hubbard model with doubly degenerate atomic orbitals, using an optimization variational Monte Carlo method. It is found that when the isolated Fermi surface overlaps the van Hove singularity points, dx2 - y2 and d + i d-wave superconducting states, among various pairing symmetries, become stabilized by large Coulomb interactions. The pairing is originating from the interaction-energy gain induced dominantly by the enhancement of antiferromagnetic spin correlations. The possibility of triplet pairing is limited for the present parameterization.",

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author = "Kenji Kobayashi and Hisatoshi Yokoyama",

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N2 - As a model of the novel superconductor Nax CoO2 · y H2 O, we study a triangular Hubbard model with doubly degenerate atomic orbitals, using an optimization variational Monte Carlo method. It is found that when the isolated Fermi surface overlaps the van Hove singularity points, dx2 - y2 and d + i d-wave superconducting states, among various pairing symmetries, become stabilized by large Coulomb interactions. The pairing is originating from the interaction-energy gain induced dominantly by the enhancement of antiferromagnetic spin correlations. The possibility of triplet pairing is limited for the present parameterization.

AB - As a model of the novel superconductor Nax CoO2 · y H2 O, we study a triangular Hubbard model with doubly degenerate atomic orbitals, using an optimization variational Monte Carlo method. It is found that when the isolated Fermi surface overlaps the van Hove singularity points, dx2 - y2 and d + i d-wave superconducting states, among various pairing symmetries, become stabilized by large Coulomb interactions. The pairing is originating from the interaction-energy gain induced dominantly by the enhancement of antiferromagnetic spin correlations. The possibility of triplet pairing is limited for the present parameterization.

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KW - Pairing symmetries

KW - Transition-metal oxides

KW - Variational method

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