Angular dependence of vortex dynamics in BaFe1.9Ni0.1As2 single crystal

Abstract

The anisotropic vortex dynamics of BaFe1.9Ni0.1As2 single crystals have been studied by rotating the crystals in magnetic fields. It is found that the upper critical field, vortex glass transition field, and flux pinning energy increase with increasing the angle θ from c-axis to ab-plane, and can be approximately described by the anisotropic Ginzburg–Landau theory. The vortex phase diagrams have been constructed from the vortex glass, pinned and unpinned vortex liquid regions to the normal states. From the critical current density investigation, we found that the δTc-pinning dominates the pinning behavior for a sample without appreciable defects such as grain boundaries which will induce the δl-pinning.