Skyrmion phase and competing magnetic orders on a breathing kagome lattice

TL;DR

This paper reports the discovery of a skyrmion lattice phase in a centrosymmetric breathing kagome lattice material, Gd3Ru4Al12, characterized by large topological Hall effect and small helical pitch, expanding skyrmion research beyond non-centrosymmetric magnets.

Contribution

It provides the first experimental observation of a skyrmion lattice in a centrosymmetric breathing kagome lattice, with detailed magnetic structure analysis and phase behavior.

Findings

Observation of skyrmion lattice with large topological Hall effect.

Identification of a very small helical pitch of 2.8 nm.

SkL is stabilized by thermal fluctuations in a specific magnetic field range.

Abstract

Magnetic skyrmion textures are realized mainly in non-centrosymmetric, e.g. chiral or polar, magnets. Extending the field to centrosymmetric bulk materials is a rewarding challenge, where the released helicity / vorticity degree of freedom and higher skyrmion density result in intriguing new properties and enhanced functionality. We report here on the experimental observation of a skyrmion lattice (SkL) phase with large topological Hall effect and an incommensurate helical pitch as small as 2.8 nm in metallic Gd3Ru4Al12, which materializes a breathing kagom\'e lattice of Gadolinium moments. The magnetic structure of several ordered phases, including the SkL, is determined by resonant x-ray diffraction as well as small angle neutron scattering. The SkL and helical phases are also observed directly using Lorentz transmission electron microscopy. Among several competing phases, the SkL is promoted over a low-temperature transverse conical state by thermal fluctuations in an intermediate range of magnetic fields.