51V-NMR study of low-temperature phase in δ-Ag2/3V2O5

Abstract

51V-NMR experiments have been performed to investigate the local magnetic and electronic properties on the phase transition in the mixed-valence oxide δ-Ag2/3V2O5. We have observed the abrupt loss of 51V-NMR signal coming from the non-magnetic V5+-like ions above Tc = 225 K. It indicates that the majority of V ions are magnetic above Tc and that the phase transition is accompanied by the charge separation and charge ordering of 3d electrons on V sites. In the charge ordered state below Tc, the magnetic V4+-like ions are located at both V1 and V2 sites with equal distribution.