Nonlinear Current–Voltage Characteristics in Composite Systems Consisting of YBCO Superconductor and Y2CoMnO6

The resistive properties of several (1) pure YBCO superconductors and (2) composite systems consisting of YBCO and the low-density multiferroic component of Y 2 CoMnO 6 (YCMO) have been studied. The current–voltage ( IV ) characteristics of underdoped YBCO superconductors have been studied by adding low-density multiferroic YCMO as an intergranular network. The nonlinear nature of IV below the critical temperature has been used to extract an exponent related to the superfluid stiffness. Variations of the exponent with temperature have been studied within the framework of Kosterlitz–Thouless (KT) transition. Within the framework of the Ambegaokar–Halperin–Nelson–Siggia (AHNS) theory, we have discussed controlling the superfluid phase stiffness as a function of temperature in different composite systems. The magnetic nature of the intergranular networks in YBCO strongly influences the superfluid phase stiffness.