Skyrmion production on demand by homogeneous DC currents

摘要

Topological magnetic textures—like skyrmions—are major players in the design of next-generation magnetic storage technology due to their stability and the control of their motion by ultra-low currents. A major challenge to develop new skyrmion-based technologies is the controlled creation of magnetic skyrmions without the need of complex setups. We show 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 and efficiently with a period that can be tuned by the applied current strength. We propose a specific experimental setup 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 the consequent dynamics w.r.t. the stabilization of topological textures. Our findings allow for skyrmion production on demand in simple ferromagnetic thin films by homogeneous DC currents.