Nanoscale Skyrmions on a Square Atomic Lattice

TL;DR

This study uses spin-polarized scanning tunneling microscopy to observe nanoscale skyrmions and complex spin textures on a square atomic lattice, revealing coexistence of phases and topological features at relatively low magnetic fields.

Contribution

It provides experimental evidence of nanoscale skyrmions on a square lattice and analyzes their topological properties, expanding understanding of skyrmion behavior in different lattice symmetries.

Findings

Observation of a zero-field spin spiral ground state

Coexistence of spin spiral and skyrmion phases at 9 T

Hexagonal arrangement of skyrmions despite square lattice symmetry

Abstract

Spin-polarized scanning tunneling microscopy has been applied to study non-collinear spin textures of a Mn monolayer on a four-fold symmetric W(001) substrate revealing a zero-field spin spiral ground state and two different types of rotational domain walls. With an applied magnetic field of 9 T, we observe a coexistence of the spin spiral and the skyrmion phase, even though a previous theoretical study reported that the phase transition occurs at 18 T. The skyrmions show a roughly hexagonal arrangement despite the square lattice symmetry of the W(001) substrate. Based on a reduced set of energy parameters, we are able to describe the experimental findings and to analyze the topological properties of the rotational domain walls.