Distinct Suppression Mechanisms of Superconductivity by Magnetic Domains and Spin Fluctuations in EuFe2(As1-xPx)2 superconductors

TL;DR

This study investigates how magnetic domains and spin fluctuations differently suppress superconductivity in EuFe2(As1-xPx)2, revealing distinct mechanisms depending on the relative transition temperatures.

Contribution

It provides the first detailed phase diagram mapping the separate effects of magnetic domains and spin fluctuations on superconductivity in this material.

Findings

Ferromagnetic multi-domain state suppresses Hc2 via Jaccarino-Peter breakdown.

Short-range spin correlations act as pair-breaking centers.

Different suppression mechanisms depend on the Tc and TFM relationship.

Abstract

Using ac composite magnetoelectric technique, we map the phase diagrams of EuFe(As1-xPx)2 to resolve the interplay between superconductivity and ferromagnetism. For samples with Tc<TFM, the transition to a ferromagnetic multi-domain state suppresses Hc2 through the breakdown of Jaccarino-Peter compensation and enhanced magnetic scattering from inter-domain disorder, while Hirr is reduced due to vortex-antivortex pair nucleation at domain walls disrupting the vortex lattice. Conversely, for samples with Tc>TFM, strong short-range spin correlations and phase boundaries within a multiphase coexistence regime near the triple point act as potent pair-breaking centers, leading to pronounced Hc2 suppression.