Determination of chirality and density control of N\'eel-type skyrmions with in-plane magnetic field

TL;DR

This study investigates how in-plane magnetic fields influence the formation, density, and chirality of Ne9el-type skyrmions in multilayer films, providing insights for their control in spintronic devices.

Contribution

It demonstrates the control of skyrmion density and chirality using in-plane magnetic fields and correlates experimental observations with micromagnetic simulations.

Findings

Skyrmions appear and evolve into snake-like structures under decreasing magnetic field.

The skyrmion velocity direction is dominated by chirality, revealing the Dzyaloshinskii-Moriya interaction sign.

In-plane magnetic fields increase skyrmion concentration.

Abstract

Magnetic skyrmions are topologically protected nanoscale spin textures exhibiting fascinating physical behaviors. Recent observations of room temperature N\'eel-type skyrmions in magnetic multilayer films are an important step towards their use in ultra-low power devices. We have investigated the magnetization reversal in a [Pt/Co/Ta]11 multilayer sample under a tilted magnetic field using the in-situ Lorentz tunneling electron microscopy. On decreasing the magnetic field individual skyrmions appear that subsequently evolve into snake-like structures growing in the direction opposite to the in-plane magnetic field. We show that this unusual relation between the velocity vector and the magnetic field is dominated by the chirality of the N\'eel-type skyrmions. It allows one to extract the sign of the Dzyaloshinskii-Moriya constant. We also demonstrate that high concentration of skyrmions can be achieved on increasing the in-plane component of the field. Our micromagnetic simulations agree with our experimental results.