Crystal growth and magnetic properties of γ-Li xV 2O 5 (0.90 ≤ x ≤ 1.00)

Abstract

A large single crystal of S = 1/2 quasi-one-dimensional system γ-LiV 2O 5 was successfully grown by the flux method. Single crystals of nonstoichiometric γ-Li xV 2O 5 were also prepared. The electromagnetic properties of γ-Li xV 2O 5 (0.90 ≤ x ≤ 1.00) were investigated. Li deficiency introduces nonmagnetic V 5+ ( S = 0) ions or holes in the magnetic V 4+ ( S = 1/2) linear chain. In γ-Li xV 2O 5, the Curie-like increase of the magnetic susceptibility was observed at low temperature, but no evidence for a magnetic order was observed, in contrast to the 1-D cuprates. The electrical resistivity of γ-Li xV 2O 5 decreases with Li deficiency at room temperature, but all compounds remain semiconductive. The temperature dependence of conductivity for the γ-Li xV 2O 5 does not obey any activation types except the stoichiometric γ-LiV 2O 5 (E a ∼ 0.32 eV). In γ-LiV 2O 5, the exchange integral through the corner of VO 5 square pyramid has been estimated to be about 3 times as large as that through the edge. Therefore the magnetic structure of γ-LiV 2O 5 can be considered to be an infinite double linear chain, rather than an infinite linear zigzag chain.