Temperature-Induced Metal-Insulator Transition in Bi_xV₈O₁₆

抄録

From the resistivity and magnetic susceptibility measurements of polycrystalline Bi_xV₈O₁₆ with 1.6<x<1.8, it was revealed for the first time that Bi_xV₈O₁₆ with 1.72<x<1.8 exhibits a temperature-induced metal-insulator transition (MIT). A large hysteresis was observed in their susceptibilities and resistivities as functions of temperature, indicating that the MIT is of the first order. The possibility of charge ordering between V³⁺ and V⁴⁺ has been discussed for the origin of the MIT in this system. In the insulating phase, Bi_xV₈O₁₆ with 1.72<x<1.8 indicates another anomaly in the magnetic susceptibility, which may imply magnetic ordering below the anomaly temperature. We suggest that the physical properties of this system are controlled by multiple order parameters including charge, spin, and orbital quanta.