Metal–insulator transition in 1 T-TaS 2− xSe x

Abstract

The transition metal dichalcogenide, 1 T-TaS 2, shows metal–insulator transition (MIT) accompanying the nearly commensurate (NC)–commensurate (C) charge density wave (CDW) phase transition at 180 K. It has been proposed that the low-temperature C-CDW phase is a Mott insulator. However, our specific heat and magnetic susceptibility measurements in the 1 T-TaS 2− x Se x system revealed no indications of effective mass enhancement or intrinsic localized spins in the insulating phase. So we propose a new model for the MIT in which the interlayer coupling of the CDW superstructure plays an important role.