It is widely believed that the skyrmion Hall effect is absent in antiferromagnets because of the vanishing topological charge. However, the Aharonov-Casher theory indicates the possibility of topological effects for neutral particles. In this Letter, we predict the skyrmion Hall effect in emerging altermagnets with zero net magnetization and zero skyrmion charge. We first show that the neutral skyrmion manifests as a magnetic quadrupole in altermagnets. We reveal a hidden gauge field from the magnetic quadrupole, which induces the skyrmion Hall effect when driven by spin transfer torque. Interestingly, we identify a sign change of the Hall angle when one swaps the anisotropic exchange couplings in altermagnets. Furthermore, we demonstrate that both the velocity and Hall angle of altermagnetic skyrmions sensitively depend on the current direction. Our findings real the critical role of magnetic quadrupole in driving the skyrmion Hall effect with vanishing charge, and pave the way to discovering new Hall effect of neutral quasiparticles beyond magnetic skyrmions.

中文翻译：

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Altermagnets 中的 Skyrmion 霍尔效应


人们普遍认为，由于拓扑电荷消失，反铁磁体中没有斯格明子霍尔效应。然而，Aharonov-Casher 理论表明了中性粒子可能存在拓扑效应。在这封信中，我们预测了零净磁化和零斯格明子电荷的新兴替代磁体中的斯格明子霍尔效应。我们首先表明，中性斯格明子在交替磁体中表现为磁四极子。我们揭示了来自磁性四极子的隐藏规范场，当由自旋转移扭矩驱动时，它会感应出斯格明子霍尔效应。有趣的是，当交换磁体中的各向异换耦合时，我们发现了霍尔角的符号变化。此外，我们证明，交磁斯格明子的速度和霍尔角都敏感地取决于电流方向。我们的研究结果真正揭示了磁四极子在用消失电荷驱动斯格明子霍尔效应的关键作用，并为发现磁斯格明子之外的中性准粒子的新霍尔效应铺平了道路。