Engineering Dzyaloshinskii-Moriya interaction in B20 thin film chiral magnets

TL;DR

This paper demonstrates the growth and characterization of epitaxial Mn_xFe_{1-x}Ge thin films on Si substrates, showing tunable Dzyaloshinskii-Moriya interaction and skyrmion sizes, enabling scalable magnetic device applications.

Contribution

It introduces a method to engineer the Dzyaloshinskii-Moriya interaction and skyrmion size in epitaxial B20 thin films through stoichiometric tuning.

Findings

Antisymmetric exchange interaction varies with manganese fraction x.

Helical period ranges from 200 nm to 8 nm.

Epitaxial growth of B20 structure on Si substrates achieved.

Abstract

Chiral magnetic Mn$_x$Fe$_{1-x}$Ge compounds have an antisymmetric exchange interaction that is tunable with the manganese stoichiometric fraction, $x$. Although millimeter-scale, polycrystalline bulk samples of this family of compounds have been produced, thin-film versions of these materials will be necessary for devices. In this study, we demonstrate the growth of epitaxial Mn$_x$Fe$_{1-x}$Ge thin films on Si (111) substrates with a pure B20 crystal structure in the stoichiometric fraction range x from 0 to 0.81. Following systematic physical and magnetic characterization including microwave absorption spectroscopy, we quantify the antisymmetric exchange interaction and helical period as a function of $x$, which ranges from 200 nm to 8 nm. Our results demonstrate an approach to engineering the size of magnetic skyrmions in epitaxial films that are grown using scalable techniques.