Perturbation Theory of Spin-Triplet Superconductivity for Sr2RuO4.

We discuss the possibility of spin-triplet superconductivity within the third order perturbation theory with respect to on-site Coulomb repulsion U . Critical temperature T c for spin-triplet pairing state is calculated in a single-band two-dimensional Hubbard model and relatively high T c is obtained for moderately large U . The present situation considered here is particularly intended for the main branch γ in Sr 2 RuO 4 . According to the calculation, third order vertex correction terms, which are not direct contribution from spin fluctuation, are important, while the bare susceptibility χ 0 ( q ) need not always have a prominent peak at q =0 for the spin-triplet pairing state. The picture that strong ferromagnetic spin fluctuations mainly induce the spin-triplet superconductivity in Sr 2 RuO 4 may not be appropriate, and such momentum dependence of renormalized effective interaction between quasi-particles as is not sufficiently taken into account in spin fluctuation mediated interaction is essential ...

[1]  T. Nomura,et al.  Magnetic Properties of Quasi-Two-Dimensional Ruthenates Studied by Mean Field Theoretical Approach , 2000 .

[2]  Y. Maeno,et al.  Changes in the Superconducting State of Sr2RuO4 under Magnetic Fields Probed by Specific Heat. , 2000 .

[3]  Ishiguro,et al.  In-plane anisotropy of upper critical field in Sr2RuO4 , 2000, Physical review letters.

[4]  M. Sigrist,et al.  The role of spin-orbit coupling for the superconducting state in Sr2RuO4 , 1999, cond-mat/9911325.

[5]  M. Takano,et al.  Spin fluctuations in the ruthenium oxides RuO 2 , SrRuO 3 , CaRuO 3 , and Sr 2 RuO 4 probed by Ru NMR , 1999 .

[6]  K. Miyake,et al.  Model for Unconventional Superconductivity of Sr2RuO4 : Effect of Impurity Scattering on Time-Reversal Breaking Triplet Pairing with a Tiny Gap , 1999 .

[7]  G. Lonzarich,et al.  P-WAVE AND D-WAVE SUPERCONDUCTIVITY IN QUASI-TWO-DIMENSIONAL METALS , 1999, cond-mat/9906091.

[8]  Y. Maeno,et al.  Evidence for Incommensurate Spin Fluctuations in Sr 2 RuO 4 , 1999, cond-mat/9904348.

[9]  S. Koikegami,et al.  Perturbation Theory on the Transition Temperature and Electronic Properties of Organic Superconductor , 1999, cond-mat/9908011.

[10]  T. M. Rice,et al.  Phenomenology of the superconducting state in Sr2RuO4 , 1999, cond-mat/9902214.

[11]  I. Mazin,et al.  Competitions in Layered Ruthenates: Ferromagnetism versus Antiferromagnetism and Triplet versus Singlet Pairing , 1999, cond-mat/9902193.

[12]  Y. Maeno,et al.  Spin-triplet superconductivity in Sr2RuO4 identified by 17O Knight shift , 1998, Nature.

[13]  Y. Maeno,et al.  Novel Character of Spin Fluctuations in Spin-Triplet Superconductor Sr2RuO4: 17O-NMR Study. , 1998 .

[14]  Y. Maeno,et al.  Time-reversal symmetry-breaking superconductivity in Sr2RuO4 , 1998, Nature.

[15]  Y. Maeno,et al.  Extremely Strong Dependence of Superconductivity on Disorder in Sr2RuO4 , 1998 .

[16]  T. M. Rice,et al.  Sr2RuO4 - A realization of spin triplet pairing? , 1997 .

[17]  Y. Maeno,et al.  Anisotropic pairing in superconducting Sr 2 RuO 4 : Ru NMR and NQR studies , 1997 .

[18]  David J. Singh,et al.  Ferromagnetic spin fluctuation induced superconductivity in Sr_2RuO_4 , 1997, cond-mat/9703068.

[19]  G. Baskaran.  Why is Sr2RuO4 not a high Tc superconductor? Electron correlation, Hund's coupling and p-wave instability , 1996 .

[20]  Fujita,et al.  Quantum oscillations in the layered perovskite superconductor Sr2RuO4. , 1996, Physical review letters.

[21]  M. S. Singh.  Relationship of Sr2RuO4 to the superconducting layered cuprates. , 1995, Physical review. B, Condensed matter.

[22]  Oguchi.  Electronic band structure of the superconductor Sr2RuO4. , 1995, Physical review. B, Condensed matter.

[23]  F. Lichtenberg,et al.  Superconductivity in a layered perovskite without copper , 1994, Nature.

[24]  T. Hotta.  Transition Temperatures in Cuprate Superconductors on the Basis of d-p Model , 1994 .

[25]  H. J. Vidberg,et al.  Solving the Eliashberg equations by means ofN-point Padé approximants , 1977 .