Crystallographic and magnetic properties of (Cu 1− xV x)V 2S 4 ( x≈0.3) single crystals with the layered defect NiAs structure synthesized under high pressure

Abstract

We report on the reproducible growth of (Cu 1− x V x )V 2S 4 single crystals of sizable dimensions (∼0.3 mm) and homogeneous composition ( x≈0.3) by means of high-pressure synthesis. The refinement of single crystal X-ray diffraction data indicates that the crystal structure is of the monoclinic defect NiAs-type, which consists of a stacking of VS 2 layers with CdI 2-type structure and chains of edge-sharing (Cu 1− x V x )S 6 octahedra. Layers and chains form a network of face-sharing octahedra with no Cu–V intra-chain ordering. A combined X-ray photoelectron spectroscopy and bond valence sum analysis indicates that the valence of the V and Cu ions are 3+ and 1+, respectively. Magnetic susceptibility measurements unveil the coexistence of a large Pauli-like and of a small Curie-like paramagnetic contributions, with no evidence of any long range order down to 2 K. This result suggests a picture of predominantly itinerant 3 d V electrons with significant electron–electron correlations.