Spatially homogeneous ferromagnetism below the enhanced Curie temperature in EuO_{1-x} thin films

TL;DR

This study uses muon probes to reveal that EuO_{1-x} thin films maintain homogeneous ferromagnetism above the standard Curie temperature, challenging previous phase separation models and supporting RKKY-like interactions.

Contribution

It provides direct evidence of homogeneous magnetic order above T_C in EuO_{1-x} thin films using muon spectroscopy, offering new insights into magnetic interactions in doped EuO.

Findings

Homogeneous magnetic order persists above the enhanced T_C.

Muon signals show a double dome feature similar to magnetization.

Results support RKKY-like interactions over phase separation models.

Abstract

We have used low energy implanted muons as a volume sensitive probe of the magnetic properties of EuO_{1-x} thin films. We find that static and homogeneous magnetic order persists up to the elevated T_C in the doped samples and the muon signal displays the double dome feature also observed in the sample magnetization. Our results appear incompatible with either the magnetic phase separation or bound magnetic polaron descriptions previously suggested to explain the elevated T_C, but are compatible with an RKKY-like interaction mediating magnetic interactions above 69 K.