Metal-Nonmetal Transition and Superconductivity Localization in the Two-Dimensional Conductor<i>κ</i>-(BEDT-TTF)<b>₂</b>Cu[N(CN)<b>₂</b>]Cl under Pressure

Abstract

The pressure phase diagram of κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl is determined by measuring the intralayer and interlayer resistivities. With increase of pressure, nonmetallic behavior of resistivity is suppressed and a metallic phase is stabilized, yielding the phase reentrance near critical pressure region. Concurrently, an incomplete superconductivity phase appearing at ambient pressure becomes to show complete superconductivity giving zero resistance when the sheet resistance becomes comparable to h /4 e 2 by the application of pressure, indicating that the superconductivity is localized in the lower pressure region. The effect of deuteration of BEDT-TTF molecule on the pressure phase diagram is also discussed.