Measurements of the shear modulus and plastic flow of vortex lattice in YBCO single crystals

In this study, we report on the current-voltage characteristics of a bridge cut out from YBCO single crystal. The de-pinning critical current and the flux flow resistance dependencies on temperature have been investigated for samples placed in a zero magnetic field and in a magnetic field of 1.5 T applied parallel to the c-axis of the crystal (H∥c). The overall observed general behavior is similar to the flux creep and flux flow behaviors that have been observed in “cold” superconductors. Down to 78 K, the glass-like behavior of used crystals is absent. Between the irreversible and the shoulder temperatures, the existence of spatially inhomogeneous vortex phase is very plausible: solid phase--in the vicinity of twins and liquid--far from twin planes. Direct measurements of the shear modulus and plastic flow of vortex lattice were performed and included.