Site-specific 13C NMR study on the locally distorted triangular lattice of the organic conductor k-(BEDT-TTF)2Cu2(CN)3

To verify the effect of geometrical frustration, we artificially distort the triangular lattice of the quasi-two-dimensional organic conductor k-(BEDT-TTF)(2)Cu-2(CN)(3) [BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene] by analogous-molecular substitution and apply C-13 NMR of bulk and substituted sites, electric conductivity, and static magnetic susceptibility measurements. The results indicate that the magnetic characteristics of the substituted sample are quantitatively similar to those of the pure sample. Moreover, the magnetic characteristics at the substituted sites are also the same as in the bulk. These results suggest that the observed magnetic properties may not be due to the geometrical frustration but the importance of disorder.