Re-entrance of resistivity due to the interplay of superconductivity and magnetism in $\ce{Eu_{0.73}Ca_{0.27}(Fe_{0.87}Co_{0.13})2As2}$

TL;DR

This study investigates how the interplay between superconductivity and magnetism causes resistivity re-entrance in a doped EuFe2As2 compound, revealing complex magnetic-superconducting interactions.

Contribution

It demonstrates the coexistence and competition of superconductivity and magnetic order in a specifically doped EuFe2As2 compound, with detailed analysis of re-entrance behavior.

Findings

Superconductivity appears above Eu magnetic order.

Resistivity re-entrance occurs when Eu magnetic order sets in.

Magnetization and susceptibility measurements support the magnetic influence on superconductivity.

Abstract

By simultaneous Co and Ca-doping we were able to obtain an $\ce{EuFe2As2}$-based compound with superconductivity appearing above the antiferromagnetic order of $\ce{Eu^{2+}}$ magnetic moments. However, as soon as the antiferromagnetic order appears a re-entrance behavior is observed \textemdash{} instead of zero resistivity and diamagnetic signal down to the temperature of \unit[2]{K}. By investigating magnetization, ac susceptibility and electrical transport properties of $\ce{Eu_{0.73}Ca_{0.27}(Fe_{0.87}Co_{0.13})2As2}$ and comparing them to previously studied M\"ossbauer effect and neutron scattering measurements of this and similar compounds an explanation of such behavior is proposed.