Spin-orbit-torque-assisted thermal octupole switching in Mn₃Sn

Non-collinear antiferromagnets, such as Mn₃X (X = Sn, Ge, etc.), are non-trivial antiferromagnets that substantially interact with currents and light due to their band topology, making them promising materials for the next-generation spintronic devices [1, 2]. Magnetic octupoles, the collective magnetic orders of non-collinear antiferromagnets, change the band structure and they can be controlled by electric currents [3]. Recently, Joule heating has also been thought to be crucial for the octupole switching [4], but the self-heating temperature has not been studied quantitatively.

Here we study the temperature excursion due to Joule heating during the octupole switching process in Mn₃Sn. The threshold current density for the switching depends on the thickness of SiO₂ layer of a Si/SiO₂ substrate, while the switching temperature is almost constant at ~460 K which is above the Néel temperature. The current density required to reach the Néel temperature is calculated analytically, and it quantitatively describes the dependence of the threshold current density on the substrate choice. This result shows that the current-driven switching is accompanied by demagnetization and reformation of the octupoles above and below the Néel temperature, respectively. This work demonstrates that temperature plays a decisive role in the octupole switching and a general guideline to calculate the Joule-heating temperature in micro-electronic devices.

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

[2] S. Nakatsuji, et al., Nature 527, 212 (2015).

[3] H. Tsai, et al., Nature 580, 608 (2020).

[4] G. K. Krishnaswamy, et al., Phys. Rev. Appl. 18, 024064 (2022).