NMR study of lineshifts and relaxation rates of the one-dimensional antiferromagnet LiCuVO4

Abstract

NMR measurements were performed on single-crystalline samples of the one-dimensional Heisenberg antiferromagnet (1D HAF) LiCuVO4. We investigated Li-7 and V-51 NMR spectra, deduced the respective lineshifts K(T), spin-lattice relaxation rates 1/T-1, and spin-spin relaxation rates 1/T-2 and 1/T-2G. The results are compared to theoretical predictions for the relaxation rates 1/T-1(T) and 1/T-2G(T) deduced from the dynamic susceptibility chi(q,omega) of a 1D HAF spin chain as proposed by Sachdev [Phys. Rev. B 50, 13006 (1994)]. We document a correspondence between the anisotropic relaxation rates derived from electron paramagnetic resonance linewidth Delta H(T) and nuclear magnetic resonance 1/T-1(T), respectively, the former being well described in the framework of symmetric anisotropic exchange interactions for LiCuVO4 by Krug von Nidda et al.