Magnetism in superconducting EuFe$_2$As$_{1.4}$P$_{0.6}$ single crystals studied by local probes

TL;DR

This study investigates the coexistence of ferromagnetism and superconductivity in EuFe2As1.4P0.6 single crystals using local magnetic probes, revealing magnetic order and changes in Fe moment dynamics below the superconducting transition.

Contribution

It provides new insights into the magnetic behavior and Fe moment dynamics in EuFe2As1.4P0.6, demonstrating coexistence of ferromagnetism and superconductivity.

Findings

Magnetic hyperfine fields appear below 18 K.

Ferromagnetism coexists with superconductivity below 15 K.

Fe magnetic moments become 'frozen' within the ab-plane below TSC.

Abstract

We have studied the magnetism in superconducting single crystals of EuFe2 As1.4 P0.6 by using the local probe techniques of zero-field muon spin rotation/relaxation and 151 Eu/57 Fe M\"ossbauer spec- troscopy. All of these measurements reveal magnetic hyperfine fields below the magnetic ordering temperature TM = 18 K of the Eu2+ moments. The analysis of the data shows that there is a coexistence of ferromagnetism, resulting from Eu2+ moments ordered along the crystallographic c-axis, and superconductivity below TSC \approx 15 K. We find indications for a change in the dynamics of the small Fe magnetic moments (\sim 0.07 \mu B) at the onset of superconductivity: below TSC the Fe magnetic moments seem to be "frozen" within the ab-plane.