Local magnetic susceptibility, spin dynamics, and charge order in the quasi-one-dimensional conductor β−Li0.33V2O5 investigated by site-selective V51 NMR

Abstract

$^{51}\mathrm{V}$ NMR measurements have been conducted on a single crystal of the quasi-one-dimensional conductor $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Li}}_{0.33}{\mathrm{V}}_{2}{\mathrm{O}}_{5}$ which undergoes a metal-insulator (MI) transition at ${T}_{\mathrm{MI}}\ensuremath{\sim}170$ K. In the metallic phase, we obtain $^{51}\mathrm{V}$ Knight shift and electric field gradient tensors. From the analysis of the $^{51}\mathrm{V}$ Knight shifts, we find that the charge disproportionation appears even in the metallic state and the electronic structure is represented within a model of weakly coupled ladders containing two types of ladders with distinct carrier densities. Based on the $^{51}\mathrm{V}$ nuclear spin-lattice relaxation rate, we discuss the spin dynamics within the one-dimensional electron gas model. From the analysis of several nonmagnetic ${\mathrm{V}}^{5+}$ spectra observed in the insulating phase, we propose a possible charge-order pattern which has a superlattice modulation larger than those in other family members of $\ensuremath{\beta}\text{\ensuremath{-}}{A}_{0.33}{\mathrm{V}}_{2}{\mathrm{O}}_{5}$ $(A=\mathrm{Na}$ and Ag). Finally, we discuss the $A$-ion dependence of the electronic structure, the charge disproportionation, and the charge order in $\ensuremath{\beta}\text{\ensuremath{-}}{A}_{0.33}{\mathrm{V}}_{2}{\mathrm{O}}_{5}$.