Ferromagnetic fluctuation and possible triplet superconductivity in Na_xCoO_2*yH_2O: Fluctuation-exchange study of multi-orbital Hubbard model

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dc.creatorMochizuki, Masahito
dc.creatorYanase, Youichi
dc.creatorOgata, Masao
dc.date2004-07-05
dc.date2005-03-10
dc.date.accessioned2026-07-07T06:21:58Z
dc.date.available2026-07-07T06:21:58Z
dc.descriptionSpin and charge fluctuations and superconductivity in a recently discovered superconductor Na_xCoO_2*yH_2O are studied based on a multi-orbital Hubbard model. Tight-binding parameters are determined to reproduce the LDA band dispersions with the Fermi surface, which consist of a large cylindrical one around the Gamma-point and six hole pockets near the K-points. By applying the fluctuation-exchange (FLEX) approximation, we show that the Hund's-rule coupling between the Co t2g orbitals causes ferromagnetic (FM) spin fluctuation. Triplet f_{y(y^2-3x^2)}-wave and p-wave pairings are favored by this FM fluctuation on the hole-pocket band. We propose that, in Na_xCoO_2*yH_2O, the Co t2g orbitals and inter-orbital Hund's-rule coupling play important roles on the triplet pairing, and this compound can be a first example of the triplet superconductor in which the orbital degrees of freedom play substantial roles.
dc.description5 pages, 3 figures
dc.identifierhttps://arxiv.org/abs/cond-mat/0407094
dc.identifierhttp://arxiv.org/abs/cond-mat/0407094
dc.identifierPhys. Rev. Lett. 94, 147005 (2005)
dc.identifierdoi:10.1103/PhysRevLett.94.147005
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/95773
dc.subjectStrongly Correlated Electrons
dc.subjectSuperconductivity
dc.titleFerromagnetic fluctuation and possible triplet superconductivity in Na_xCoO_2*yH_2O: Fluctuation-exchange study of multi-orbital Hubbard model
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