Vortex dynamic, pinning and irreversibility field investigation in EuRbFe4As4 superconductor

V. A. Vlasenko; K. S. Pervakov; S. U. Gavrilkin

doi:10.1088/1361-6668/ab9aa5

paper

Vortex dynamic, pinning and irreversibility field investigation in EuRbFe4As4 superconductor

arXiv:1906.04597 · doi:10.1088/1361-6668/ab9aa5

Abstract

We performed systematic AC susceptibility and magnetic moment measurements to investigate the vortex dynamics and pinning in the $E u R b F e_{4} A s_{4}$ single crystal as a function of temperature, frequency, and DC magnetic field. The vortex solid-liquid line was determined and it fits well with $H (T_{p}) = H_{0} (1 - t_{p})^{β}$ using $β$ =1.74-1.91, for $H ∥ ab$ . It indicates a rather high pinning strength of the vortex system. The activation energy $U_{0}$ was determined from thermally activated flux creep theory and reached 6700 K at low fields, suggesting strong vortex pinning. A field dependence of $U_{0} (H ∥ ab) \sim H^{a}$ with $a = 0.47$ suggests thermally activated plastic pinning or caused by planar defects. Magnetic moment measurements also confirmed strong pinning in a $E u R b F e_{4} A s_{4}$ superconductor and the superconducting response gives the main contribution to the $M (H)$ hysteresis. Additionally, we found evidence of long-range magnetic interactions in $E u^{2 +}$ sublattice and the FM-like nature of $E u^{2 +}$ atoms ordering.