Onset of a skyrmion phase by chemical substitution in MnGe chiral magnet

TL;DR

This study demonstrates that chemical substitution in MnGe alloys induces a skyrmion phase, which is absent in pure MnGe, and highlights how doping can tune skyrmion properties over broad temperature and field ranges.

Contribution

It reveals the emergence of a skyrmion phase in MnGe alloys through Fe doping, providing new insights into controlling skyrmion states via chemical substitution.

Findings

Skyrmion lattice appears only with Fe substitution.

Skyrmion density is exceptionally high in doped samples.

Skyrmion phase persists over large temperature and field ranges.

Abstract

We study the evolution of the magnetic phase diagram of Mn$_{1-x}$Fe$_{x}$Ge alloys with concentration $x$ ($0 \leq x \leq 0.3$) by small-angle neutron scattering. We unambiguously observe the absence of a skyrmion lattice (or A-phase) in bulk MnGe and its onset under a small Mn/Fe substitution. The A-phase is there endowed with an exceptional skyrmion density, and is stabilized within a very large temperature region and a field range which scales with the Fe concentration. Our findings highlight the possibility to fine-tune properties of skyrmion lattices by means of chemical doping.