Fluxoid motion and resistive transition in high Tc superconductors

Abstract

Significantly broad resistive transition has been observed in high temperature superconductors under a magnetic field. A similar broad transition was observed by French et al. in resistance versus magnetic field characteristics in low temperature superconductors for various current densities. In this case, the critical current density and the flow resistivity completely determine the overall resistive characteristics. This suggests that the resistive characteristics in high temperature superconductors may also be determined by these two quantities alone. In fact, the procedure outlined reproduces the commonly observed resistive characteristics. A notable feature determined from this procedure is that a knee exists in the resistance versus temperature curve. This projection corresponds to the irreversibility point, i.e. the temperature at which the critical current density is reduced to zero.