Numerical study on the transport phenomena in the antiferromagnetic skyrmion system

The antiferromagnetic (AFM) skyrmion has attracted attention due to its promising application to memory devices; the AFM skyrmion is free from the stray fields and the skyrmion Hall effect, which has been preventing the application of the ferromagnetic skyrmion. [1] Despite the intensive theoretical investigations [2, 3] and the recent observation of the AFM skyrmion phase in a bulk system [4], the fundamental properties of the AFM skyrmion, such as the transport phenomena, are yet to elucidate. While the topological Hall effect in FM skyrmion phases has been closely investigated for various parameter regions [5], the studies on the transport phenomena in AFM skyrmion phases are limited to the strong coupling regime [6].
In this study, we numerically calculate the topological charge and spin Hall conductivity for the AFM skyrmion system. Exploiting the state-of-the-art real-space calculation method (kernel polynomial method), we investigate the transport phenomena of the AFM skyrmion system for various skyrmion sizes and coupling strengths. We investigate for which parameter region the concept of the emergent magnetic field holds valid in the AFM background. We further discuss the effect of non-adiabaticity on the transport phenomena and reveal the difference with that in the FM background.

[1] B. Göbel et al., Physics Reports 895, 1-28 (2021)
[2] H. D. Rosales et al., Phys. Rev. B 92, 214439 (2015)
[3] R. Ozawa et al., Phys. Rev. Lett. 118, 147205 (2017)
[4] S.Gao et al., Nature 586, 37-41 (2020)
[5] AM et al., arXiv:2103.12343
[6] B. Göbel et al., Phys. Rev. B 96, 060406(R) (2017)