Competition between the modification of intrinsic superconducting properties and the pinning landscape under external pressure in CaKFe$_4$As$_4$ single crystals

TL;DR

This study investigates how external pressure influences the superconducting properties and vortex pinning landscape in CaKFe$_4$As$_4$ single crystals, revealing a transition to non-superconducting behavior above a structural phase change.

Contribution

It provides new insights into the interplay between intrinsic superconductivity and vortex pinning under pressure in CaKFe$_4$As$_4$, highlighting the effects of structural transitions.

Findings

Superconducting properties evolve with pressure up to 7.5 GPa.

Flux creep rate slows down under pressure.

Superconductivity diminishes or disappears above the structural transition.

Abstract

Measurements of low field magnetization, trapped flux magnetization and 5 K flux creep in single crystal of CaKFe$_4$As$_4$ under pressure up to 7.5 GPa in a diamond pressure cell are presented. The observed evolution of the temperature dependence of the self-field critical current and slowing down of the base temperature flux creep rate are explained within the two sources of pinning hypothesis involving presence of CaKFe$_4$As$_4$ intergrowths suggested in the literature. Above the half collapsed tetragonal structural transition under pressure, where superconductivity is non-bulk or absent, critically diminished or no diamagnetism and flux trapped magnetization were observed.