Geometric frustration in CuV2S4

A cubic spinel conductor CuV2S4, containing the corner-sharing tetrahedral lattice of V, was investigated. Above a structural transition at 90 K, the 51V nuclear spin-relaxation rate 1/T1 is comparatively large in magnitude and tends to saturate at higher temperatures, indicating that the V lattice behaves as a nearly antiferromagnetic metal. By substituting nonmagnetic Sn for V, the susceptibility turns to be of Curie–Weiss type and 51V-1/T1 temperature-independent, suggesting recovery of hidden spins as a result of a partial release of the frustration. These results lead to the conclusion that CuV2S4 is an itinerant-electron frustrated system as YMn2. The CDW transition of CuV2S4 accompanied by a tetragonal distortion which may be understood as a result of lowering of interaction dimensionality inherent to the corner-sharing tetrahedral lattice.