Topological Spin-Orbit Torque in Ferrimagnetic Weyl Semimetal

Spin-orbit torque (SOT) is an electrically generated spin torque from spin-orbit coupling, enabling flexible magnetization control. The SOT conventionally comes from Fermi surfaces and suffers from energy dissipation. A potential solution is to use magnetic Weyl semimetals (MWSMs). MWSMs have nontrivial point nodes (Weyl points), which can yield topological responses and also suppression of dissipation due to small Fermi surfaces. However, the SOT from the Fermi sea, called the "topological SOT" is still unclear in MWSMs, while conventional SOT from Fermi surfaces was confirmed [1].

In this talk, we propose topological SOT in the compensated ferrimagnetic Weyl semimetal Ti₂MnAl. With a tight-binding model[2], we derive a sizable topological SOT achieving an efficiency 10-1000 times higher than previous studies of SOT. By investigating mixed Berry curvature, which is the Berry curvature extended in the composite space of momentum and magnetization, we reveal that topological SOT arises from the mirror symmetry breaking in Ti₂MnAl [3].

[1] D. Kurebayashi, Y. Araki, and K. Nomura, J. Phys. Soc. Jpn. 90, 084702(2021).

[2] T. Meguro, A. Ozawa, K. Kobayashi, and K. Nomura, J. Phys. Soc. Jpn. 93, 034703 (2024).

[3] T. Meguro, A. Ozawa, K. Kobayashi, Y. Araki, and K. Nomura, arXiv:2409.07106.