Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, Ilha do Fundao, 21941-972 Rio de Janeiro, Brazil.
Nat Commun. 2013;4:2892. doi: 10.1038/ncomms3892.
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 Mn2Au is not a Pauli paramagnet as hitherto believed but an antiferromagnet with Mn moments of ~4 μB. 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 Mn2Au the most promising material for antiferromagnetic spintronics identified so far.
自旋电子器件的尺寸不断缩小，需要开发对寄生外磁场不敏感的结构，同时保持基于巨磁电阻或隧道磁电阻现有系统的磁电阻信号。这可以通过在隧道各向异性磁电阻结构中加入反铁磁材料而不是铁磁材料来实现。为了将这一有前途的概念转化为实际设备，必须确定具有大自旋轨道效应的新型磁性材料。在这里，我们证明 Mn2Au 不是迄今为止所认为的 Pauli 顺磁体，而是一个具有约 4 μB Mn 磁矩的反铁磁体。交换相互作用的特别强导致外推的奈尔温度远远高于 1000 K，因此基本保持了基态磁特性，直到室温以上。再加上存在显著的面内各向异性，这使得 Mn2Au 成为迄今为止确定的最有前途的反铁磁自旋电子学材料。
