Source-linked AI summary
Control of Dzyaloshinskii-Moriya interaction in Mn$_{1-x}$Fe$_x$Ge: a first-principles study
Takashi Koretsune, Naoto Nagaosa, Ryotaro Arita
TL;DR
Engineering skyrmions in metallic Mn1−xFexGe requires control of the DM interaction, which is linked to skyrmion size and helicity. Using first-principles calculations, the paper reproduces the observed sign change and connects DM behavior to band anticrossings, including strain-induced anisotropy.
Problem
Controlling skyrmion size and helicity in metallic Mn1−xFexGe requires understanding how the DM interaction can be tuned through the electronic structure.
Source: p. 1Method
The authors use ab initio DFT band structures to evaluate the off-diagonal spin susceptibility as a measure of the DM interaction and analyze its relation to band anticrossings.
Source: pp. 1–2Results
The calculations reproduce the experimental DM sign change between MnGe and FeGe and relate carrier-density dependence to the distribution of band anticrossing points.
Source: pp. 1, 4Takeaways & Limitations
Carrier density and exchange splitting can control the DM interaction, while strain offers a route to induce strong DM anisotropy in metallic helimagnets.
Source: pp. 1, 4The calculations use the rigid-band approximation, whose robustness is checked by applying it to MnGe’s endpoint electronic structure.
Source: p. 4
Abstract
from arXiv · showhide
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.