Origin of room temperature ferromagnetism in homogeneous (In,Mn)As thin films

TL;DR

This study investigates the microstructure of (In,Mn)As thin films grown by MOVPE to understand the origin of their room temperature ferromagnetism, emphasizing the role of homogeneous solid solutions over secondary phases.

Contribution

It demonstrates that room temperature ferromagnetism in (In,Mn)As films originates from a homogeneous solid solution rather than Mn-rich precipitates, using TEM analysis.

Findings

Homogeneous (In,Mn)As films exhibit room temperature ferromagnetism.

MnAs precipitates are present only in high Mn concentration films.

Ferromagnetism is linked to the (In,Mn)As solid solution.

Abstract

The microstructure of (In,Mn)As thin films grown using metalorganic vapor phase epitaxy (MOVPE) was investigated to determine the origin of room temperature ferromagnetism in these films. Transmission electron microscopy (TEM) based techniques were used to investigate phase purity and compositional homogeneity. Microanalysis of an In1-xMnxAs film with x = 0.01 and a Curie temperature of 330 K exhibited a homogeneous distribution of Mn. High Mn concentration films with x = 0.20 exhibited MnAs precipitates within the (In,Mn)As matrix. The analysis indicates that room temperature ferromagnetic, single-phase (In,Mn)As can be formed by MOVPE. The origin of ferromagnetism is attributed to (In,Mn)As solid solution rather than distinct secondary Mn-rich magnetic phase(s).