A new class of chiral materials hosting magnetic skyrmions beyond room temperature

TL;DR

This paper reports the discovery of chiral magnetic skyrmions existing at and above room temperature in a new class of cubic chiral magnets, expanding potential for spintronic applications.

Contribution

It demonstrates the formation of skyrmions in beta-Mn-type Co-Zn-Mn alloys at and above room temperature, surpassing previous temperature limitations in chiral magnetic materials.

Findings

Skyrmions observed at and above room temperature.

Skyrmion crystal formation confirmed by LTEM, magnetization, and SANS.

Skyrmions present in both thin-plate and bulk forms.

Abstract

Skyrmions, topologically protected vortex-like nanometric spin textures in magnets, have been attracting increasing attention for emergent electromagnetic responses and possible technological applications for spintronics. In particular, metallic magnets with chiral and cubic/tetragonal crystal structure may have high potential to host skyrmions that can be driven by low electrical current excitation. However, experimental observations of skyrmions have so far been limited to below room temperature for the metallic chiral magnets, specifically for the MnSi-type B20 compounds. Toward technological applications, it is crucial to transcend this limitation. Here we demonstrate the formation of skyrmions with unique spin helicity both at and above room temperature in a family of cubic chiral magnets: beta-Mn-type Co-Zn-Mn alloys with a different chiral space group from that of B20 compounds. Lorentz transmission electron microscopy (LTEM), magnetization, and small angle neutron scattering (SANS) measurements unambiguously reveal the formation of a skyrmion crystal under the application of magnetic field (H<~1 kOe) in both thin- plate (thickness<150 nm) and bulk forms.