Proton NMR linewidth and relaxation-rate study of an organic conductor with an antiferromagnetic ground state

The inhomogeneous broadening of the proton NMR line which occurs at the Néel temperature of bis(tetramethyltetrathiafulvalene) thiocyanate [(TMTTF)2 SCN] is used to determine the magnitude of the sublattice magnetization in the antiferromagnetic state. A value of order 0.1 B is obtained, comparable to those for other salts in the family. The spin-lattice relaxation rate shows a relatively strong, asymmetric lambda anomaly at the transition. Two features in T1(T) at higher temperature are interpreted in terms of rotation of inequivalent methyl groups. © 1984 The American Physical Society.