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Spin Fluctuation-Induced Superconductivity in κ-BEDT-TTF Compounds

Hisashi Kondo·Tôru Moriya
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Abstract

Spin fluctuation-induced superconductivity in quasi-two dimensional organic compounds, κ-BEDT-TTF salts, is investigated within a fluctuation exchange (FLEX) approximation using a half-filled Hubbard model with a right-angled isosceles triangular lattice (transfer matrices -τ, -τ^\prime), extending a previous work above T_c. An energy gap of A_2 or (x^2-y^2)-type develops with decreasing temperature below T_c more rapidly than in the BCS model. The calculated dynamical susceptibilities enough below T_c show sharp resonance peaks like those in certain cuprates superconductors. The calculated nuclear spin-lattice relaxation rate 1/T_1 shows a T^3 behavior below T_c in accordance with experiment. Estimated values of 1/T_1 are roughly consistent with experimental results. A prediction is made for the doping concentration dependence of T_c and the antiferromagnetic and superconductive instability points are calculated in the U/τvs. τ^\prime/τplane.

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Hisashi Kondo, Tôru Moriya. 1999-03-25. Spin Fluctuation-Induced Superconductivity in κ-BEDT-TTF Compounds. https://doi.org/10.1016/s0921-4526(99)00872-8

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