Wernert Luke, Pradenas Bastián, Tchernyshyov Oleg, Chen Hua
Colorado State University, Department of Physics, Fort Collins, Colorado 80523, USA.
Johns Hopkins University, William H. Miller III Department of Physics and Astronomy, Baltimore, Maryland 21218, USA.
Phys Rev Lett. 2025 Jan 10;134(1):016706. doi: 10.1103/PhysRevLett.134.016706.
Noncollinear antiferromagnets (AFMs) have recently attracted attention in the emerging field of antiferromagnetic spintronics because of their various interesting properties. Because of the noncollinear magnetic order, the localized electron spins on different magnetic sublattices are not conserved even when spin-orbit coupling is neglected, making it difficult to understand the transport of spin angular momentum. Here we study the conserved Noether current due to spin-rotation symmetry of the local spins in noncollinear AFMs. Interestingly, we find that a Hall component of the spin current can be generically created by a longitudinal driving force associated with a propagating spin wave, inherently distinguishing noncollinear AFMs from collinear ones. We coin the corresponding Hall coefficient, an isotropic rank-four tensor, as the Hall (inverse) mass, which generally exists in noncollinear AFMs and their polycrystals. The resulting Hall spin current can be realized by spin pumping in a ferromagnet-noncollinear AFM bilayer structure as we demonstrate numerically, for which we also give the criteria of ideal boundary conditions. Our results shed light on the potential of noncollinear AFMs in manipulating the polarization and flow of spin currents in general spintronic devices.
非共线反铁磁体（AFM）由于其各种有趣的性质，最近在反铁磁自旋电子学这一新兴领域引起了关注。由于非共线磁序，即使忽略自旋轨道耦合，不同磁子晶格上的局域电子自旋也不守恒，这使得理解自旋角动量的输运变得困难。在此，我们研究了非共线反铁磁体中由于局域自旋的自旋旋转对称性而产生的守恒诺特定流。有趣的是，我们发现自旋电流的霍尔分量通常可以由与传播的自旋波相关的纵向驱动力产生，这从本质上区分了非共线反铁磁体与共线反铁磁体。我们将相应的霍尔系数，即一个各向同性的四阶张量，命名为霍尔（逆）质量，它通常存在于非共线反铁磁体及其多晶体中。正如我们通过数值演示的那样，通过在铁磁体 - 非共线反铁磁体双层结构中进行自旋泵浦可以实现由此产生的霍尔自旋电流，对此我们还给出了理想边界条件的标准。我们的结果揭示了非共线反铁磁体在一般自旋电子器件中操纵自旋电流的极化和流动方面的潜力。
