Magnetic Octupole Dynamics in Non-collinear Antiferromagnets

Antiferromagnetic spintronics has attracted significant interest due to its potential for ultra-dense, ultra-fast information devices, well-suited for high-performance information technologies [1]. D0₁₉-type non-collinear antiferromagnets are particularly intriguing, because, unlike conventional antiferromagnets, they exhibit pronounced transport and optical responses [2]. These responses are governed by the electronic band structure, which is closely tied to the magnetic octupole moment, a counterpart to the magnetic dipole moment in ferromagnets. In this talk, I will explore the dynamics of the magnetic octupole moments in the non-collinear antiferromagnetic Weyl semimetal, Mn₃Sn. First, I will discuss our experimental study on current-driven octupole switching, where we demonstrate that the critical switching temperature remains largely constant above the Néel temperature [3]. Based on these results, we propose the reconfiguration process of magnetic octupoles from the demagnetized state. In the second part, I will present a numerical investigation of the domain-wall motion in non-collinear antiferromagnets, using a micromagnetic model. Our calculations show field-driven motion of a 180˚ octupole domain wall, resulting from the complex interplay among 60˚ domain walls. This work provides deeper insights into the dynamics of magnetic multipoles in antiferromagnets and advances our understanding of antiferromagnetic spintronics.

This work was done in collaboration with Virginia Lorenz, David Cahill, and Axel Hoffmann.

[1] S. A. Siddiqui et al., J. Appl. Phys. 128, 040904 (2020).

[2] T. Chen et al., Nat. Commun. 12, 572 (2021).

[3] M.-W. Yoo et al., APL Mater. 12, 081107 (2024).