Evidence of finite-size effects in anS=1/2Heisenberg linear chainLiV2O5studied by51VNMR

Nuclear magnetic resonance (NMR) spectra of ${}^{51}\mathrm{V}$ nuclei were measured in $S=1/2\mathrm{}$ Heisenberg linear chains, ${\mathrm{LiV}}_2{\mathrm{O}}_5$ and ${\mathrm{Li}}_x{\mathrm{V}}_2{\mathrm{O}}_5\hspace{0.5em}(x=0.98\mathrm{}$ and 0.95). Broad double-peak structure was observed for the pure ${\mathrm{LiV}}_2{\mathrm{O}}_5$ and the linewidth increased with the decrease in temperature and the increase in field. The increase of the linewidth became prominent for Li-deficient samples. These experimental facts prove that the staggered moments are induced in a whole system due to the existence of open ends in the chains. The NMR spectra for 2% and 5% Li-deficient samples were interpreted by considering the correlation length of finite-size chains with odd and even number spins.