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.

Department of Structure Analysis Institute of Physics ASCR Na Slovance 2 Praha 18221 Czech Republic

Dresden High Magnetic Field Laboratory Helmholtz Zentrum Dresden Rossendorf Dresden D 01328 Germany

Forschungsneutronenquelle Heinz Maier Leibnitz FRM 2 Technische Universität München Lichtenbergstrasse 1 Garching 85747 Germany

Institut Laue Langevin BP 156 Grenoble Cedex 9 38042 France

Max Planck Institute for Chemical Physics of Solids Nöthnitzer Str 40 Dresden D 01187 Germany

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