Characterization of a Disordered Above Room Temperature Skyrmion Material Co8Zn8Mn4

TL;DR

This paper reports the synthesis and detailed characterization of a polycrystalline Co8Zn8Mn4 sample that hosts a disordered skyrmion phase above room temperature, with insights into its magnetic and structural properties.

Contribution

It provides a comprehensive synthesis and multi-technique characterization of a disordered skyrmion material, including methods to orient and order the skyrmion lattice.

Findings

Skyrmion phase exists between 305 K and 315 K.

SANS reveals a rotationally disordered skyrmion lattice.

Magnetic field sequences can order the skyrmion lattice.

Abstract

Topologically non trivial spin textures host great promise for future spintronic applications. Skyrmions in particular are of burgeoning interest owing to their nanometric size, topological protection, and high mobility via ultra-low current densities. It has been previously reported through magnetic susceptibility, microscopy, and scattering techniques that Co$_{8}$Zn$_{8}$Mn$_{4}$ forms an above room temperature triangular skyrmion lattice. Here we report the synthesis procedure and characterization of a polycrystalline Co$_{8}$Zn$_{8}$Mn$_{4}$ bulk sample. We employ powder x-ray diffraction, backscatter Laue diffraction, and neutron diffraction as characterization tools of the crystallinity of the samples, while magnetic susceptibility and Small Angle Neutron Scattering (SANS) measurements are performed to study the skyrmion phase. Magnetic susceptibility measurements show a dip anomaly in the magnetization curves which persists over a range of approximately 305 K- 315 K. SANS measurements reveal a rotationally disordered polydomain skymrion lattice. Applying a recently developed symmetry-breaking magnetic field sequence, we were able to orient and order the previously jammed state to yield the prototypical hexagonal diffraction patterns, with secondary diffraction rings.