Control of Dzyaloshinskii-Moriya interaction in Mn$_{1-x}$Fe$_x$Ge: a first-principles study

TL;DR

This study uses first-principles calculations to understand and control the Dzyaloshinskii-Moriya interaction in Mn$_{1-x}$Fe$_x$Ge, revealing how its sign and magnitude can be tuned for skyrmion applications.

Contribution

It demonstrates the systematic understanding and control of DM interaction sign and magnitude in metallic helimagnets through electronic structure analysis and strain application.

Findings

Reproduced the sign change of DM interaction observed experimentally.

Showed DM interaction depends on carrier density and electronic structure details.

Induced large anisotropy in DM interaction via strain engineering.

Abstract

Motivated by the recent experiment on the size and helicity control of skyrmions in Mn$_{1-x}$Fe$_x$Ge [K. Shibata et al., Nature Nanotechnology 8, 732 (2013)], we study how the Dzyaloshinskii-Moriya (DM) interaction changes its size and sign in metallic helimagnets. By means of first-principles calculations, we successfully reproduce the non-trivial sign change of the DM interaction observed in the experiment. While the DM interaction sensitively depends on the carrier density or the detail of the electronic structure such as the size of the exchange splitting, its behavior can be systematically understood in terms of the distribution of anticrossing points in the band structure. By following this guiding principle, we can even induce gigantic anisotropy in the DM interaction by applying a strain to the system. These results pave the new way for skyrmion crystal engineering in metallic helimagnets.