Critical Current and Pinning Features of a CaKFe4As4 Polycrystalline Sample.

Armando Galluzzi,Gaia Grimaldi,Massimiliano Polichetti,Antonio Leo,Francesca Varsano,Andrea Masi,Angela Nigro

doi:10.3390/ma14216611

Abstract

We analyze the magnetic behavior of a CaKFe4As4 polycrystalline sample fabricated by a mechanochemically assisted synthesis route. By means of DC magnetization (M) measurements as a function of the temperature (T) and DC magnetic field (H) we study its critical parameters and pinning features. The critical temperature Tc has been evaluated by M(T) curves performed in Zero Field Cooling-Field Cooling conditions. These curves show the presence of a little magnetic background for temperatures above Tc, as also confirmed by the hysteresis loops M(H). Starting from the M(H) curves, the critical current density Jc of the sample has been calculated as a function of the field at different temperatures in the framework of the Bean critical state model. The Jc(H) values are in line with the ones reported in the literature for this typology of samples. By analyzing the temperature dependence of the critical current density Jc(T) at different magnetic fields, it has been found that the sample is characterized by a strong type pinning regime. This sample peculiarity can open perspectives for future improvement in the fabrication of this material.

Highlights

This value is approximately 35 K and it is consistent with the values reported in the literature [1,21,22]. It is worth noting the presence of a slight non-zero signal above Tc in the ZFC curve as already reported in other works on iron-based systems [23,24,25,26], which can be limited by improving the fabrication processes [26,27,28]
We have studied the magnetic response of a CaKFe As polycrystalline sample by We have studied the magnetic response of a CaKFe44As44 polycrystalline sample by using DC magnetization measurements as a function of the temperature and magnetic field
From the analysis of the Zero Field Cooling M(T) curve, Tc has been found equal to slight magnetic background has been found in the M(T) and M(H) curves for T > Tc

Summary

Introduction

Until 2016, with the discovery of the 1144 Iron-Based superconductors (IBSs) family [1], the 122 and 11 IBS families have been the most studied due to their low anisotropy values, high values of critical current density Jc , irreversibility field and upper critical field [2,3,4,5,6,7,8,9,10] In this framework, the 1144 family [1] attracted significant interest in recent years due to the stoichiometric nature of its layered structure. The 1144 and 122 compounds are both characterized by the intercalation of mixed Alkaline (A)

Methods

Results

Conclusion