Mid-gap state formed inside Mott gap of 1T-TaS2 single crystals and metal-insulator transition

We have measured electrical resistivity, Hall coefficient, thermoelectric power, and magnetization for charge-density, wave (CDW) material 1T-TaS2 single crystals grown by varying the excess sulfur content x(es). We have revealed that a small mid-gap state is joined inside the Mott gap and that anomalous low, temperature transport is not governed by the Mott gap state itself but by the mid-gap state, The electric properties of the mid-gap state are modified by increasing x, (or hole doping), and we have found the insulator-metal transition occurs by hole doping below 60 K.