Effect of heat diffusion on current-driven magnetization switching in non-collinear antiferromagnets

Non-collinear antiferromagnets (AFs) are interesting for spintronics [1], since they exhibit large anomalous Hall and magneto-optical Kerr effects, which can be used for detecting their magnetic order [2]. Furthermore, their magnetic order can be modulated electrically by spin-orbit torques [3]. The magnetization switching requires a temperature sufficiently close to the Néel temperature [4]. However, the temperature by Joule heating is dependent on heat diffusion by adjacent substrates.

Here, we show the effect of heat flow to substrates on the critical current for magnetization switching in non-collinear AF Mn₃Sn. We fabricate Hall bar devices using polycrystalline W/Mn₃Sn multilayers on thermally-oxidized Si substrates with different thicknesses of SiO₂ layers, h. Different thicknesses of the oxide layer result in temperature differences between the devices when identical electric currents are applied. The devices show similar behavior under field-driven switching. However, in the case of current-driven switching, the coercive current, I_c, is dependent on h. This behavior can be explained by a heat-diffusion model, , when h > 300 nm. If h is thinner than 50 nm, however, I_c is smaller than the analytic model.

[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).