Awaking of ferromagnetism in GaMnN through control of Mn valence

TL;DR

This study demonstrates that mild hydrogenation of GaMnN thin films induces room temperature ferromagnetism by altering Mn valence states, supporting a model where coexisting Mn2+ and Mn3+ ions mediate magnetic coupling.

Contribution

It reveals that hydrogenation can control Mn valence in GaMnN, awakening ferromagnetism without secondary phases, advancing understanding of magnetic mechanisms in dilute magnetic semiconductors.

Findings

Hydrogenation changes Mn valence from +3 to +2.

Room temperature ferromagnetism is induced after hydrogenation.

No secondary phases detected in the samples.

Abstract

Room temperature ferromagnetism of GaMnN thin films is awaked by a mild hydrogenation treatment of samples synthesized by molecular beam epitaxy. Local environment of Mn atoms is monitored by Mn-L2,3 near edge x-ray absorption fine structure (NEXAFS) technique. Doped Mn ions are present at substitutional sites of Ga both before and after the hydrogenation. No secondary phase can be detected. Major valency of Mn changes from +3 to +2 by the hydrogenation. The present result supports the model that the ferromagnetism occurs when Mn2+ and Mn3+ are coexistent and holes in the mid- gap Mn band mediate the magnetic coupling.