13C-NMR study on partially deuterized κ-(BEDT-TTF)2Cu[N(CN)2]Br

Using partially deuterized BEDT-TTF molecules, we performed C-13-NMR study of a series of partially deuterized K(BEDT-TTF)(2)Cu[N(CN)(2)]Br salts, where BEDT-TTF is bis-(ethylenedithio)tetrathiafulvalene. We synthesized partially deuterized BEDT-TTF molecules C-13-enriched on only one side of the central carbon sites. The substitution of one side of the central carbon avoid the Pake doublet and we can estimate the density of states from the Knight-shift and the spin-lattice relaxation rate. The reduced mass effect predicted from the specific heat measurement near the SC-AFI boundary was not observed in the C-13-NMR measurement but the phase separation behavior was observed.