Multicritical Phenomena of Superconductivity and Antiferromagnetism in Organic Conductor $\kappa$-(BEDT-TTF)${}_2$X

Abstract

We study theoretically the multicritical phenomena of the superconductivity (SC) and antiferromagnetism (AF) in organic conductors $\kappa$-BEDT salts. The phase diagram and the experimental data on the NMR relaxation rate $1/T_1$ is analysed in terms of the renormalization group method. The bicritical phenomenon observed experimentally indicates the rotational symmetry, i.e., SO(5) symmetry, of the SC and the AF. The critical exponent $x$ for the divergence of $1/T_1$ is well explained by $x=\nu (z-1-\eta )$ with the dynamical exponent $z=3/2$ for the AF region while $z=\varphi /\nu \sim 1.84$ at the bicritical point. These results strongly suggest that the origin of the SC is in common with that of the AF and that its symmetry is d-wave.

5 pages, REVTEX, 3 figures

References in corpus (2)

• Origin of Superconductivity in 2D-Organic Compounds and High-T_c Cuprates
• Effects of Disorder on the Competition between Antiferromagnetism and Superconductivity

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