Non-Korringa nuclear spin relaxation in the organic superconductor (BEDT-TTF)2Cu[N(CN)2]Br

Abstract The temperature dependence of the proton spin-lattice relaxation rate T 1 −1 in the organic superconductor (BEDT-TTF) 2 Cu[N(CN) 2 ]Br ( T c = 11.6 K) shows a strong deviation from Korringa behaviour above 40 K. Comparison of the T 1 −1 ( T ) results with the spin susceptibility data suggests that antiferromagnetic spin fluctuations give an important contribution to the measured relaxation rate in the normal state.