Linear and nonlinear resistivity of YBa2Cu3O7−δ ceramics at chiral-glass transition

Abstract

Ceramic YBa2Cu3O7−δ composed of sub-micron size grains has shown successive phase transitions under zero field. The first transition occurs inside each grain at Tc1 and the second transition occurs among the grains at Tc2 (<Tc1). We measured the current–voltage characteristics and estimated the linear and nonlinear resistivity. The linear resistivity remains finite below Tc2. The nonlinear resistivity has a broad peak above Tc2 and diminishes continuously toward Tc2 with decreasing temperature. These results are in good agreement with the theoretical analysis and suggest that chiral-glass ordering occurs at Tc2.