Energy-efficient generation of skyrmion phases in Co/Ni/Pt-based multilayers using Joule heating

TL;DR

This study demonstrates energy-efficient methods to generate and stabilize skyrmions in Co/Ni/Pt multilayers using Joule heating, with optimized parameters reducing energy input and broadening material applicability.

Contribution

The paper introduces a novel approach to form skyrmions via Joule heating, significantly lowering energy requirements and enabling stable skyrmions in various magnetic field conditions.

Findings

Joule heating induces stripe-to-skyrmion transformation.

Reduced magnetic moment lowers energy and field thresholds.

Skyrmions are stable across wide magnetic field ranges.

Abstract

We have studied the effects of electrical current pulses on skyrmion formation in a series of Co/Ni/Pt-based multilayers. Transmission X-ray microscopy reveals that by applying electrical current pulses of duration and current density on the order of $\tau$=50 $\mu$s and j=1.7x10$^1$$^0$ A/m$^2$, respectively, in an applied magnetic field of $\mu$$_0$Hz=50 mT, stripe-to-skyrmion transformations are attained. The skyrmions remain stable across a wide range of magnetic fields, including zero field. The skyrmions then remain stable across a wide range of magnetic fields, including zero field. We primarily attribute the transformation to current-induced Joule heating on the order of ~125 K. Reducing the magnetic moment and perpendicular anisotropy using thin rare-earth spacers dramatically reduces the pulse duration, current density, and magnetic field necessary to 25 $\mu$s, 2.4x10$^9$ A/m$^2$, and 27 mT, respectively. These findings show that energetic inputs allow for the formation of skyrmion phases in a broad class of materials and that material properties can be tuned to yield more energy-efficient access to skyrmion phases.