Powder Spectra of ⁵¹V NMR in CuV₂S₄: Possible Coexistence of Charge and Spin Density Waves

Abstract

NMR experiments are reported for the copper chalcogenide spinel CuV : S 4 , which has incommensurate lattice distortions at low temperatures in spite of the cubic symmetry at high temperature. A broad spin-echo spectrum of 51 V has been observed below 90 K at 17 MHz. but it shows a remarkable frequency dependence where it becomes sharper with decreasing frequency. Possible coexistence of charge and spin density waves is suggested at low temperatures in this material.

Correlation between structural and magnetic properties of half‐metallic spinel CuV2S4 due to the order–disorder transition of 3d2(t2g) orbitals of V3+ ions

“…12 from that reported in [1,3,4,6]. The latter data had a sharp decrease at 90 K. The sin- gle crystal and the fine powders used in the present investigations were grown by Nagata's group, who already reported the important magnetic, electric, and thermal properties of CuV 2 S 4 [7,8,10,11,15,16]. At the moment, it is not easy for us to explain the origin of the difference, though we think that the results depend on the type of specimen used -one single crystal, single crystals, polycrystalline fine powders, and polycrystals -in addition to the instrumental condition of the measurements, because the susceptibility depends on correlation between the crystallographic orientation of the specimen used and the direction and strength of the applied magnetic field.…”

“…After the CDW interpretations of the structural, electric, and magnetic anomalies [1], many investigations were carried out of the structural, magnetic, and electric properties of CuV 2 S 4 in the low-temperature region by means of X-ray diffraction [2][3][4][5], magnetic susceptibility [2,3,[5][6][7], electrical resistivity [2,5,[7][8][9][10], and NMR [4][5][6][11][12][13][14], in addition to the electronic density of states (DOS) [15][16][17]. Lu et al [15] argued using X-ray photoemission and X-ray spectroscopy that Cu ions are in the mono-valent state in Structural and magnetic properties of the spinel CuV 2 S 4 have been studied by means of X-ray diffraction using synchrotron radiation and measurements of magnetic susceptibility.…”