Anomalous magnetisation in a Fe_3Pt-FeRh film occurring at T~120 K in the field-cooled-cooling curves for low magnetic fields

TL;DR

This study reports an anomalous magnetization near 120 K in a Fe_3Pt-FeRh film under low magnetic fields, resembling a metamagnetic transition, likely due to small antiferromagnetic Fe-Rh clusters undetectable by X-ray diffraction.

Contribution

It reveals a temperature-specific anomalous magnetization in Fe-Rh/Fe_3Pt films linked to small antiferromagnetic clusters, expanding understanding of magnetic transitions in such layered systems.

Findings

Anomalous magnetization occurs near 120 K in low fields.

Metamagnetic-like transition broadens with aging.

X-ray diffraction does not detect Fe-Rh antiferromagnetic phase.

Abstract

We report on an anomalous magnetization observed with temperature for low magnetic fields applied in the plane of a film formed by a thin layer of Fe-Rh deposited on a thin foil of ordered Fe$_3$Pt. The anomalous effect resembles a metamagnetic transition and occur only in the field-cooled-cooling magnetization curve at temperatures near 120 K. We also observe an aging effect which broads the metamagnetic-like transition suggesting the existence of Fe-Rh antiferromagnetic clusters which apparently are too small to be detected by the x-ray diffraction.The X-Ray diffractogram obtained in the Fe-Rh surface of the film do not show the Fe-Rh antiferromagnetic phase (a=2.98 $\AA$) but peaks at same locations of those found for the pure ordered Fe$_3$Pt film (a=3.72 $\AA$)