Evidence of a spin-density-wave transition in the organic conductor (methylenedithiotetrathiafulvalene${)}_2$Au(CN${)}_2$ [(MDT-TTF${)}_2$Au(CN${)}_2$]

The low-temperature electronic state of the title compound has been examined by ${}_{}{}^1{}_{}{}^{}\mathrm{NMR}$ measurements. An enhancement of the nuclear-spin–lattice relaxation rate and a broadening of the NMR absorption line at low temperatures below the metal-insulator transition in conductivity were observed. These results are clear evidence that this compound undergoes a spin-density-wave transition at low temperatures, while the electronic state is suggested to be two dimensional by structure, transport, and EPR studies.