Nonlinear Effects near the Superconducting Transition of Organic Synthetic Metal (TMTSF)₂ClO₄

Abstract

Two types of nonlinear effects in the electrical conductivity along the most conductive a -axis of (TMTSF) 2 ClO 4 were observed near the superconducting transition temperature. Along the a -axis, the resistivity decreased as decreasing the temperature between 300 K and 5.5 K and turned to increase down to 1.07 K below which the superconductivity appeared. One of the nonlinearities was the increase in resistance up to a value greater than the normal one at a current just above the superconducting critical current. Along the c * -axis, the least conductive axis, such nonlinearity was not observed. The other is the decrease in resistance driven by the current much larger than the critical current, which seems to show the restoration of the metallic behavior. The influences of thermally induced microcracks on the temperature dependence of resistivity and to the nonlinearities are also presented.