Topological antiferromagnetic spin valve

在FM/NM/FM三层（FM：铁磁体，NM：非磁体）中，两个FM磁矩之间的相对取向的变化可能导致隧道电流的变化：这种隧道磁阻（TMR）与FM的自旋极化成正比，如Julliere模型所描述的那样，因此它通常不会在自旋极化可以忽略的反铁磁体中看到。在这里，我们证明了反铁磁TMR的存在，在磁性八极阀Mn 3Sn/MgO/Mn 3Sn，支持的理论。值得注意的是，尽管自旋极化率比Fe的自旋极化率小三个数量级，但Mn 3Sn/MgO/Mn 3Sn显示出比Fe/MgO/Mn 3S大5倍的TMR。这强调了八极极化的主导作用，而不是自旋极化。

In FM/NM/FM trilayers (FM: ferromagnet, NM: nonmagnet), the change of relative orientation between the two FM moments could lead to varying opposition to the tunneling current flow: this tunneling magnetoresistance (TMR) is proportional to the spin polarization of FMs as is characterized by the Julliere’s model, and thus it is not usually seen in antiferromagnets with negligible spin polarization. Here, we demonstrate the existence of antiferromagnetic TMR in a magnetic octupole valve Mn3Sn/MgO/Mn3Sn, supported by the theory. Remarkably, although the spin polarization rate is three orders smaller than that of Fe, Mn3Sn/MgO/Mn3Sn shows 5 times larger TMR than Fe/MgO/Mn3S. This emphasizes the dominant role of octupole polarization, instead of spin polarization.