Kirill Belashchenko
The spin-splitter effect is the generation of a pure transverse spin current without the need for spin-orbit coupling, which is a promising application of altermagnets in spintronic devices. Without strain, this effect is not allowed by symmetry in g-wave altermagnets. Using first-principles calculations mapped to a realistic symmetry-enforced k-p model, I will discuss that shear strain in the basal plane induces a strong spin-splitter effect in hole-doped semiconducting MnTe, with a giant gauge factor of more than 30 [1]. In contrast, this gauge factor is of order 1 in metallic g-wave altermagnets. The giant effect in MnTe is mediated by the lifting of the orbital degeneracy at the valence band edge by the strain-induced crystal field. Next, I will explain that the spin splitting effect is generically allowed in non-cubic ferromagnets thanks to the crystallographic anisotropy of the conductivity tensor [2]. First-principles screening of 41 noncubic ferromagnets combined with the Boltzmann calculations in the relaxation-time approximation revealed that many of them, when grown as a single crystal with tilted crystallographic axes, can exhibit large spin splitting angles comparable with the best available spin-orbit-driven spin Hall sources. Finally, I will discuss piezomagnetic response in altermagnets, both in the nonrelativistic limit and with spin-orbit coupling taken into account, based on a spin-group analysis [3]. The mechanisms of piezomagnetic response and first-principles calculations for a few altermagnets will also be discussed.
[1] K. D. Belashchenko, Phys. Rev. Lett. 134, 086701 (2025).[2] K. D. Belashchenko, Phys. Rev. B 109, 054409 (2024).
[3] M. Khodas, S. Mu, I. I. Mazin, and K. D. Belashchenko, arXiv:2506.06257.