Two-Step Structural Modulations and Fermi Liquid State in Spinel Compound CuV_2S_4(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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We have studied the magnetic, transport and structural properties of chalcogenide spinel compound CuV_2S_4 using a high-quality polycrystalline sample, in order to clarify the intrinsic physical properties of CuV_2S_4 The magnetic susceptibility and the electrical resistivity exhibit two sharp anomalies. One is reversible for temperature T_<t1> = 91.5 K and the other shows a thermal hysteresis of about 4K at T_<t2> = 56 K. We clearly observed for the first time that both anomalies are accompanied with two-step structural modulations. The crystal structure changes the symmetry form cubic to tetragonal at T_<t1>, and then the lattice constant is modulated discontinuously at T_<t2> without changing the symmetry In addition, the paramagnetic susceptibility is very large, and the electrical resistivity at low temperatures shows a quadratic temperature dependence with the coefficient A = 0.05μΩcm/K^2, which is larger than that of conventional metals These results indicate that CuV_2S_4 exhibits a Fermi-liquid-like behavior with strongly correlated electrons at lower temperatures.
社団法人日本物理学会の論文
2004-12-15