Revealing the properties of Mn2Au for antiferromagnetic spintronics

The continuous reduction in size of spintronic devices requires the development of structures, which are insensitive to parasitic external magnetic fields, while preserving the magnetoresistive signals of existing systems based on giant or tunnel magnetoresistance. This could be obtained in tunnel anisotropic magnetoresistance structures incorporating an antiferromagnetic, instead of a ferromagnetic, material. To turn this promising concept into real devices, new magnetic materials with large spin-orbit effects must be identified. Here we demonstrate that Mn 2 Au is not a Pauli paramagnet as hitherto believed but an antiferromagnet with Mn moments of ~4 μ B . The particularly large strength of the exchange interactions leads to an extrapolated Néel temperature well above 1,000 K, so that ground-state magnetic properties are essentially preserved up to room temperature and above. Combined with the existence of a significant in-plane anisotropy, this makes Mn 2 Au the most promising material for antiferromagnetic spintronics identified so far. Few of the known antiferromagnetic materials are suitable for use in spintronic devices. Here, the authors show that Mn 2 Au, which was believed to be paramagnetic, is an antiferromagnet, combining high Néel temperature and in-plane anisotropy, thus demonstrating its potential for antiferromagnetic spintronics.