51V-NMR study of charge order induced by cation order in δ-Ag2/3V2O5

International Conference on Strongly Correlated Electron Systems 2016

Kawasaki, Y.^1 ; Morioka, R.^1 ; Kishimoto, Y.^1 ; Nakamura, K.^1 ; Nishiyama, K.^2 ; Koyama, T.^2 ; Mito, T.^2 ; Baba, T.^3 ; Yamauchi, T.^3 ; Isobe, M.^4 ; Ueda, Y.^5

Graduate School of Science and Technology, Tokushima University, Tokushima

770-8506, Japan^1

Graduate School of Material Science, University of Hyogo, Hyogo

678-1297, Japan^2

Institute for Solid State Physics, University of Tokyo, Kashiwa

277-8581, Japan^3

Max Planck Institute for Solid State Research, Stuttgart

D-70569, Germany^4

Toyota Physical and Chemical Research Institute, Nagakute, Aichi

480-1192, Japan^5

关键词: Cation ordering;    Charge ordering;    Charge separations;    Magnetic and electronic properties;    Microscopic points;    Nuclear spin lattice relaxation rate;    Temperature dependence;    Thermal activation;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/807/6/062001/pdf
DOI  :  10.1088/1742-6596/807/6/062001

来源: IOP

【 摘 要 】

51V-NMR experiments have been performed to investigate the local magnetic and electronic properties of the mixed-valence oxide δ-Ag2/3V2O5, which shows the novel V4+/V5+charge ordering trigged by Ag ion ordering. We have observed the abrupt loss of51V-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 Tcand that the phase transition is accompanied by the charge separation and the charge ordering of 3d electrons on V sites. In the lowerature phase below Tc, the nuclear spin-lattice relaxation rate 1/T1shows the thermal activation-type temperature dependence with the activation energy of about 130 K. It has been clarified that the ground state of this material is the charge ordered one with the spin singlet of 3d electrons on V4+-V4+pair from a microscopic point of view.