Competing Magnetic States in the Candidate Altermagnet GdAlGe

TL;DR

This study investigates the magnetic properties of GdAlGe films, revealing a transition from bulk-like to 2D behavior with mixed magnetic states, anomalous Hall effect, and exchange bias, advancing understanding of nanoscale altermagnets for spintronics.

Contribution

It provides the first detailed analysis of magnetism and electron transport in GdAlGe films across different thicknesses, highlighting the interplay of altermagnetism and ferromagnetism in 2D limits.

Findings

GdAlGe exhibits anomalous Hall effect and negative magnetoresistance.

Magnetic state admixture increases as films approach monolayer thickness.

Intrinsic exchange bias observed due to coexistence of magnetic states.

Abstract

Altermagnetism, a newly discovered magnetic order, combines zero net magnetization with non-relativistic spin splitting of electronic bands. Its ability to utilize the advantages of both antiferromagnets and ferromagnets is highly promising for spintronic applications. Currently, the merge of altermagnetism and weak ferromagnetism in a single material excites significant interest as it provides additional control mechanisms over material properties. However, the role of dimensionality in this interplay is yet to be explored. Here, we study magnetism and electron transport in epitaxial films of the candidate altermagnet GdAlGe ranging from bulklike to a single monolayer. The films exhibit the anomalous Hall effect and negative magnetoresistance. In contrast to altermagnetic GdAlSi, the candidate altermagnet GdAlGe demonstrates an admixture of the ferromagnetic state which contribution increases as the system approaches the 2D limit. The coexistence of the magnetic states induces technologically important intrinsic exchange bias. The present work underpins future studies and applications of nanoscale altermagnets.