Metal - insulator transition in CuIr 2S 4 : Comparison with CuIr 2Se 4

Abstract

CuIr 2S 4 exhibits a sharp metal-insulator transition around 230 K. The metal-insulator transition of CuIr 2S 4 is ascribed to the structural phase transition from the cubic high-temperature metallic phase to the tetragonal low-temperature insulating phase. There is no localized magnetic moment in both of metallic and insulating phases. On the other hand, CuIr 2Se 4 stays metallic down to 0.5 K without any anomaly. The magnetic susceptibility of CuIr 2Se 4 shows a weak positive temperature dependence of dχ/dT>0 with rather large diamagnetism of core electrons, which might indicate a characteristic of strongly-correlated electrons.