Irreversibility line and thermally activated flux flow in Micro-bridges of high-temperature superconductor

摘要

We have studied the electrical resistivity as a function of temperature in Micro-bridges of YBa_(2)Cu_(3)O_(7-δ)deposited by laser ablation on the SrTiO_(3)substrate face, around superconducting transition region in different magnetic fields. The activation energy U_(0)was determined and discussed using the Arrhenius relation. The irreversibility line B_(irr)and the upper critical field B_(c2)were obtained using 10% and 90% criteria of the normal-state resistivity value from ρ (T) curves. A phase diagram of the studied sample is constructed showing the Tg glass line and a very broad vortex-liquid phase regime.