Room-temperature tetragonal non-collinear Heusler antiferromagnet Pt2MnGa.

Sanjay Singh,A Senyshyn,C Felser,Y Skourski,V Petricek,E Suard,S Chadov,L Chapon,J Nayak,S W D’Souza,M Nicklas

doi:10.1038/ncomms12671

Abstract

Antiferromagnetic spintronics is a rapidly growing field, which actively introduces new principles of magnetic storage. Despite that, most applications have been suggested for collinear antiferromagnets. In this study, we consider an alternative mechanism based on long-range helical order, which allows for direct manipulation of the helicity vector. As the helicity of long-range homogeneous spirals is typically fixed by the Dzyaloshinskii–Moriya interactions, bi-stable spirals (left- and right-handed) are rare. Here, we report a non-collinear room-temperature antiferromagnet in the tetragonal Heusler group. Neutron diffraction reveals a long-period helix propagating along its tetragonal axis. Ab-initio analysis suggests its pure exchange origin and explains its helical character resulting from a large basal plane magnetocrystalline anisotropy. The actual energy barrier between the left- and right-handed spirals is relatively small and might be easily overcome by magnetic pulse, suggesting Pt2MnGa as a potential candidate for non-volatile magnetic memory.

Highlights

Antiferromagnetic spintronics is a rapidly growing field, which actively introduces new principles of magnetic storage
Non-collinear planar AFMs without mirror symmetry, such as Mn3Ir, are predicted to exhibit the anomalous Hall[10,11], Kerr, magnetic circular dichroism (MCD) and other effects characterized by the same spatial tensor shape[12], which were not encountered in the AFM systems so far
Despite the cycloidal order seeming to be more ubiquitous for applications, the aforementioned degeneracy between the left- and right-handed magnetic screws in crystals with inversion symmetry might be considered as an alternative advantage, since it allows the direct association of a bit of information with the helicity

Summary

Introduction

Antiferromagnetic spintronics is a rapidly growing field, which actively introduces new principles of magnetic storage. We demonstrate such an AFM screw-spiral magnetic order in the tetragonal Pt2MnGa Heusler system, revealed by neutron diffraction experiments.

Results

Conclusion