Vortex phase diagram in 1111-type CaFe0.89Co0.11AsF single crystal

Studying the vortex properties in high-Tc superconductors is crucial for understanding the high temperature superconducting mechanism. However, until now, only few vortex studies have been performed in 1111-type iron-based superconductors due to their smaller-sized single crystals. In this study, we have synthesized the millimeter-sized CaFe0.89Co0.11AsF single crystals by self-flux method. Three dimensional vortex nature was confirmed in the thermally activated flux flow region. Second magnetization peak was observed on the isothermal magnetization curves. Meanwhile, the dominated role of the normal point pinning was also confirmed. Finally, the various phase boundaries of the vortex were determined based on the analysis of the resistivity and magnetization data, and a complete vortex phase diagram of CaFe0.89Co0.11AsF single crystals was established.

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

We have studied the electrical resistivity as a function of temperature in Micro-bridges of YBa2Cu3O7-δ deposited by laser ablation on the SrTiO3 substrate face, around superconducting transition region in different magnetic fields. The activation energy U0 was determined and discussed using the Arrhenius relation. The irreversibility line Birr and the upper critical field Bc2were 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.