Thermally assisted skyrmions creation in Pt/Co/Ta multilayer films

TL;DR

This study investigates how temperature influences the creation of Neel-type magnetic skyrmions in Pt/Co/Ta multilayer films, revealing thermal effects are critical for skyrmion nucleation and density control.

Contribution

It provides the first detailed in-situ analysis of temperature-dependent skyrmion formation and behavior in multilayer films using Lorentz transmission electron microscopy.

Findings

Skyrmions can be nucleated from ferromagnetic saturation states.

Maximum skyrmion density varies with temperature.

Thermal history critically affects skyrmion creation.

Abstract

N\'eel-type magnetic skyrmions in multilayer films have attracted significant amount of attention recently for their stability at room temperature and capability of motion driven by a low-density electrical current, which can be potentially applied to spintronic devices. However, the thermal effect on the formation of the skyrmions and their behavior has rarely been studied. Here, we report a study on the creation of skyrmions in [Pt/Co/Ta]10 multilayer samples at different temperatures using an in-situ Lorentz transmission electron microscopy. By imaging the magnetization reversal process from positive (negative) saturation to negative (positive) saturation, we found that the skyrmions can be created by nucleation from ferromagnetic saturation state and by breaking the labyrinth domains under certain external fields. By tuning the external fields, a maximum density of skyrmions was reached at different temperatures. The key finding is that the creation of the skyrmions in the multilayers depends critically on the temperature and thermal history.