Current-voltage characteristics and vortex dynamics of superconducting Ba0.54K0.46Fe2As2 single crystal

We have investigated the current (I) - voltage (V) characteristics and vortex dynamics of Ba0.54K0.46Fe2As2 single crystal (BaK122) in H‖ab-plane and H‖c-axis orientations. The single crystal has been prepared by conventional growth method using self flux and characterized by onset Tc = 38.5 K, ΔTc = 1.0 K (offset-onset criterion) and residual resistivity ratio (RRR) ≈ 8. Usually for high-Tc superconductors, I - V curve shows exponential behavior due to flux creep at low magnetic field and it changes to near-linear nature with increase of magnetic field due to flux flow. We have shown that I -V characteristics differ significantly in H‖ab orientations compared to H‖c orientation which might be due to the presence of second magnetization peak (SMP). We have also estimated the activation energy using the Arrhenius plot in the thermally activated flux flow (TAFF) regime from the temperature dependent resistivity curves in both field orientation and have shown the variation of activation energy with magnetic field.