Magneto-resistance and vortex phase diagram of BaNi0.1Fe1.9As2 single crystal

Abstract

The transition from vortex glass to a liquid phase is studied in BaNi0.1Fe1.9As2 single crystal with Tc = 19.4 K by magneto-resistance measurements. The resistivity curves are measured in magnetic fields in a range of 0 T–13 T for H ‖ c and H⊥c. Good scalings for all values of resistivity ρ(H, T) and the effective pinning potential U0 (H, T) are obtained with the modified vortex glass theory by using the critical exponents s and H0. Phase diagrams for H ‖ c and H⊥c are determined based on the obtained vortex glass temperature Tg, the vortex dimensionality crossover temperature T*, and the upper critical magnetic field Hc2. Our results suggest that both below and above 5 T, single vortex pinning co-exists with collective creep, and collective creep is dominant. There is a narrower vortex liquid region for H⊥c than for H ‖ c in the vortex phase diagram, which may originate from a stronger pinning force.