近日，德国马克斯·普朗克微结构物理研究所的Stuart S. P.Parkin及其研究团队取得一项新进展。经过不懈努力，他们构建出原子极限下的扭转辅助全反铁磁隧道结。相关研究成果已于2024年8月14日在国际权威学术期刊《自然》上发表。

本文展示了一种扭转策略，用于构建直至原子极限的全反铁磁隧道结。通过扭转两层二维反铁磁体（AFM）CrSBr，整个扭转堆叠作为隧道势垒，在零场（ZF）下实现了超过700%的非易失性隧穿磁阻（TMR）比。这是通过扭转两层CrSBr单层实现的，其TMR来源于跨各个CrSBr单层的累积相干隧穿。TMR对扭转角的依赖性是根据电子平行动量依赖的跨扭转单层的衰减计算得出的。

这与研究人员考虑扭转角从0°到90°变化的实验结果高度一致。此外，研究人员还发现，与未扭转的结相比，扭转结的TMR的温度依赖性惊人地更弱，这使得扭转结在应用方面更具吸引力。这项研究表明，有可能将非易失性磁信息存储推向原子级薄度的极限。

据悉，反铁磁自旋电子学在高密度和超高速信息器件方面展现出巨大潜力。磁隧道结（MTJ）是一种关键的自旋电子存储器件，通常由铁磁材料制成，而最近使用反铁磁材料制成的磁隧道结发展迅速。

附：英文原文

Title: Twist-assisted all-antiferromagnetic tunnel junction in the atomic limit

Author: Chen, Yuliang, Samanta, Kartik, Shahed, Naafis A., Zhang, Haojie, Fang, Chi, Ernst, Arthur, Tsymbal, Evgeny Y., Parkin, Stuart S. P.

Issue&Volume: 2024-08-14

Abstract: Antiferromagnetic spintronics shows great potential for high-density and ultrafast information devices. Magnetic tunnel junctions (MTJs), a key spintronic memory component that are typically formed from ferromagnetic materials, have seen rapid developments very recently using antiferromagnetic materials. Here we demonstrate a twisting strategy for constructing all-antiferromagnetic tunnel junctions down to the atomic limit. By twisting two bilayers of CrSBr, a 2D antiferromagnet (AFM), a more than 700% nonvolatile tunnelling magnetoresistance (TMR) ratio is shown at zero field (ZF) with the entire twisted stack acting as the tunnel barrier. This is determined by twisting two CrSBr monolayers for which the TMR is shown to be derived from accumulative coherent tunnelling across the individual CrSBr monolayers. The dependence of the TMR on the twist angle is calculated from the electron-parallel momentum-dependent decay across the twisted monolayers. This is in excellent agreement with our experiments that consider twist angles that vary from 0° to 90°. Moreover, we also find that the temperature dependence of the TMR is, surprisingly, much weaker for the twisted as compared with the untwisted junctions, making the twisted junctions even more attractive for applications. Our work shows that it is possible to push nonvolatile magnetic information storage to the atomically thin limit.

DOI: 10.1038/s41586-024-07818-x

Source: https://www.nature.com/articles/s41586-024-07818-x