1202.1908 (Yoshihiko Ihara et al.)

13C NMR study of superconductivity near charge instability realized in
beta"-(BEDT-TTF)4[(H3O)Ga(C2O4)3]C6H5NO2    [PDF]

Yoshihiko Ihara, Harumi Seki, Atsushi Kawamoto

To investigate the superconducting (SC) state near a charge instability, we
performed ^{13}C NMR experiments on the molecular superconductor
beta"-(BEDT-TTF)_{4}[(H_{3}O)Ga(C_{2}O_{4})_{3}]C_{6}H_{5}NO_{2}, which
exhibits a charge anomaly at 100 K. The Knight shift which we measured in the
SC state down to 1.5 K demonstrates that Cooper pairs are in spin-singlet
state. Measurements of the nuclear spin-lattice relaxation time reveal strong
electron-electron correlations in the normal state. The resistivity increase
observed below 10 K indicates that the enhanced fluctuation has an electric
origin. We discuss the possibility of charge-fluctuation-induced
superconductivity.

View original: http://arxiv.org/abs/1202.1908