NMR study of lineshifts and relaxation rates of the one-dimensional antiferromagnetLiCuVO4

Abstract

NMR measurements were performed on single-crystalline samples of the one-dimensional Heisenberg antiferromagnet (1D HAF) ${\mathrm{LiCuVO}}_{4}$. We investigated $^{7}\mathrm{Li}$ and $^{51}\mathrm{V}$ 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 $\ensuremath{\chi}(\mathbf{q},\ensuremath{\omega})$ 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 $\mathrm{\ensuremath{\Delta}}H(T)$ and nuclear magnetic resonance $1∕{T}_{1}(T)$, respectively, the former being well described in the framework of symmetric anisotropic exchange interactions for ${\mathrm{LiCuVO}}_{4}$ by Krug von Nidda et al. [Phys. Rev. B 65, 134445 (2002)].