The interplay between electronic transport and antiferromagnetic order has attracted a surge of interest as recent studies show that a moderate change in the spin orientation of a collinear antiferromagnet may have a significant effect on the electronic band structure. Among numerous electrical probes to read out such a magnetic order, unidirectional magnetoresistance (UMR), where the resistance changes under the reversal of the current direction, can provide rich insights into the transport properties of spin-orbit-coupled systems. However, UMR has never been observed in antiferromagnets before, given the absence of intrinsic spin-dependent scattering. Here, we report a UMR in the antiferromagnetic phase of a $\mathrm{FeRh}/\mathrm{Pt}$ bilayer, which undergoes a sign change and then increases strongly with an increasing external magnetic field, in contrast to UMRs in ferromagnetic and nonmagnetic systems. We show that Rashba spin-orbit coupling alone cannot explain the sizable UMR in the antiferromagnetic bilayer and that field-induced spin canting distorts the Fermi contours to greatly enhance the UMR by 2 orders of magnitude. Our results can motivate the growing field of antiferromagnetic spintronics and suggest a route to the development of tunable antiferromagnet-based spintronics devices.

中文翻译：

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反铁磁体/重金属双层中的单向磁阻

电子输运和反铁磁有序之间的相互作用引起了人们的极大兴趣，因为最近的研究表明，共线反铁磁体的自旋方向的适度变化可能对电子能带结构产生重大影响。在众多用于读取这种磁序的电探针中，单向磁阻 (UMR) 可以为自旋轨道耦合系统的传输特性提供丰富的见解，其中电阻在电流方向的反转下发生变化。然而，鉴于没有固有的自旋相关散射，以前从未在反铁磁体中观察到 UMR。在这里，我们报告了一个反铁磁相的UMR$\mathrm{铷铁}/铂$与铁磁和非磁系统中的 UMR 相比，双层会发生符号变化，然后随着外部磁场的增加而强烈增加。我们表明，单独的 Rashba 自旋轨道耦合无法解释反铁磁双层中相当大的 UMR，并且场诱导的自旋倾斜扭曲了费米轮廓，从而将 UMR 大大提高了 2 个数量级。我们的研究结果可以推动反铁磁自旋电子学领域的发展，并为开发基于可调谐反铁磁自旋电子学器件提供了一条途径。