Vortex dynamic, pinning and irreversibility field investigation in EuRbFe4As4 superconductor

TL;DR

This study investigates vortex dynamics, pinning mechanisms, and magnetic interactions in EuRbFe4As4 superconductor through systematic AC susceptibility and magnetic measurements, revealing strong vortex pinning and magnetic ordering.

Contribution

It provides new insights into vortex pinning strength, activation energy, and magnetic interactions in EuRbFe4As4, highlighting its robust vortex pinning and magnetic properties.

Findings

High vortex pinning strength indicated by the vortex solid-liquid line.

Activation energy U0 reaches 6700 K at low fields, showing strong pinning.

Evidence of long-range magnetic interactions and FM-like ordering of Eu2+ atoms.

Abstract

We performed systematic AC susceptibility and magnetic moment measurements to investigate the vortex dynamics and pinning in the $EuRbFe_4As_4$ single crystal as a function of temperature, frequency, and DC magnetic field. The vortex solid-liquid line was determined and it fits well with $H(T_p)=H_0(1-t_p)^\beta$ using $\beta$=1.74-1.91, for $H\parallel ab$. 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 $U_0(H\parallel ab)\sim H^a$ with $a=0.47$ suggests thermally activated plastic pinning or caused by planar defects. Magnetic moment measurements also confirmed strong pinning in a $EuRbFe_4As_4$ superconductor and the superconducting response gives the main contribution to the $M(H)$ hysteresis. Additionally, we found evidence of long-range magnetic interactions in $Eu^{2+}$ sublattice and the FM-like nature of $Eu^{2+}$ atoms ordering.