Skyrmion production on demand by homogeneous DC currents

TL;DR

This paper presents a method to generate skyrmions in ferromagnetic thin films using homogeneous DC currents, eliminating the need for complex setups or Dzyaloshinskii-Moriya interactions, enabling controlled and on-demand skyrmion creation.

Contribution

It introduces a novel approach to produce skyrmions via static loss of stability induced by homogeneous DC currents without Dzyaloshinskii-Moriya interactions.

Findings

Skyrmions can be created periodically and controllably with tunable periods.

The method is feasible with simple materials like cobalt-based ferromagnetic films.

Adding chiral interactions affects the dynamics but not the initial creation process.

Abstract

Topological magnetic textures - like skyrmions - have become a major player in the design of next-generation magnetic storage technology due to their stability and the control of their motion by ultra-low current densities. A major challenge to develop this new skyrmion-based technology is to achieve the controlled and deterministic creation of magnetic skyrmions without the need of complex setups. We demonstrate a solution to this challenge by showing how to create skyrmions and other magnetic textures in ferromagnetic thin films by means of a homogeneous DC current and without requiring Dzyaloshinskii-Moriya interactions. This is possible by exploiting a static loss of stability arising from the interplay of current-induced spin-transfer torque and a spatially inhomogeneous magnetization, which can be achieved, e.g., by locally engineering the anisotropy, the magnetic field, or other magnetic interactions. The magnetic textures are created controllably, efficiently, and periodically with a period that can be tuned by the applied current strength. We propose specific experimental setups realizable with simple materials, such as cobalt based materials, to observe the periodic formation of skyrmions. We show that adding chiral interactions will not influence the basics of the generations but then influence the consequent dynamics with respect to the stabilization of topological textures. Our findings allow for the production of skyrmions on demand in simple ferromagnetic thin films by homogeneous DC currents.