Vortex dynamic, pinning and irreversibility field investigation in EuRbFe4As4 superconductor

Abstract

We performed systematic AC susceptibility and magnetic moment measurements to investigate the vortex dynamics and pinning in a EuRbF e 4 As 4 single crystal as a function of temperature, frequency and DC magnetic field. The vortex solid to vortex liquid line was determined and well fitted by H(T p ) = H 0 (1 − t p ) b with b=1.74-1.91 for H c indicating rather high pinning strength of vortex system.The field dependence of the activation energy U 0 is gained within the approach of thermally activated flux creep theory. A power law dependence of U ∼ H a with a = 0.52 is observed below 1T. The activation energy reaches 6700K at low fields, suggesting strong pinning in the material. Magnetic moment measurements also confirms the strong pinning in EuRbF e 4 As 4 . We show Eu 2+ magnetic ordering suppressed in magnetic fields about 3T.

Optimization of superconducting properties of the stoichiometric CaKFe4As4

“…However, in the high field region U 0 tends to decrease faster than with field. Furthermore, the range of U 0 is much smaller than that reported for single crystal of iron-based superconductors, indicating a lower pinning force for this 1144 polycrystalline sample, as compared with single crystals, which in turn, will affect the values of the critical current densities [31][32][33] .…”

Topological magnetic order and superconductivity in EuRbFe$_4$As$_4$

“…39 On the other hand, EuRbFe 4 As 4 undergoes a superconducting transition above the magnetic one (T c > T m ). These findings motivated intensive theoretical [40][41][42][43][44] and experimental 39,[45][46][47][48][49][50][51][52][53][54][55][56][57][58] works in order to understand the interplay between these two antagonistic phenomena.…”