2005/05/13 by Seiichiro Onari, Ryotaro Arita, Kazuhiko Kuroki +1 · 10 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Charge (physics) #Charge density wave #Condensed matter physics #Coulomb #Degenerate energy levels #Electron #Fermi level #Fermi surface #Hubbard model #Ising model #Magnetic and transport properties of perovskites and related materials #Pairing #Phase (matter) #Phase diagram #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Spin (aerodynamics) #Square lattice #Superconductivity #Van Hove singularity #cond-mat.supr-con
paper · pdf · doi:10.1143/jpsj.74.2579
published in Journal of the Physical Society of Japan 74(9), 2579-2585 (Physical Society of Japan) · 7 pages, 12 figures
arxiv created 2005/05/13 · openalex publication_date 2005/09/15 · openalex created_date 2016/07/22 · openalex updated_date 2026/08/05
The pairing symmetry in the electron mechanism for superconductivity is explored when charge fluctuations coexist with spin fluctuations. The extended Hubbard model is adopted to obtain, with the fluctuation exchange approximation, a phase diagram against the on-site Coulomb repulsion U and the off-site repulsion V for the square lattice with second-neighbor hopping t'. We have found that (i) for large U(>9) a triplet superconductivity with a sin(kx+ky) symmetry can appear just below the charge density wave phase. The pairing is degenerate with sin(kx-ky), so a chiral sin(kx+ky)+isin(kx-ky) that breaks the time reversal symmetry should result, which is a candidate for the gap function on the gamma band of Sr2RuO4 and is consistent with a recent measurement of the specific heat. (ii) By systematically deforming the Fermi surface with varied t', we have identified the region where the triplet pairing is most favored to be the region where the Fermi surface traverses the van Hove singularity with the charge susceptibility strongly enhanced.