Zero-field skyrmionic states and in-field edge-skyrmions induced by boundary tuning

Jonas Spethmann,Elena Y Vedmedenko,André Kubetzka,Roland Wiesendanger,Kirsten Von Bergmann

doi:10.1038/s42005-021-00796-w

Abstract

When magnetic skyrmions are moved via currents, they do not strictly travel along the path of the current, instead their motion also gains a transverse component. This so-called skyrmion Hall effect can be detrimental in potential skyrmion devices because it drives skyrmions towards the edge of their hosting material where they face potential annihilation. Here we experimentally modify a skyrmion model system—an atomic Pd/Fe bilayer on Ir(111)—by decorating the film edge with ferromagnetic Co/Fe patches. Employing spin-polarized scanning tunneling microscopy, we demonstrate that this ferromagnetic rim prevents skyrmion annihilation at the film edge and stabilizes skyrmions and target states in zero field. Furthermore, in an external magnetic field the Co/Fe rim can give rise to skyrmions pinned to the film edge. Spin dynamics simulations reveal how a combination of different attractive and repulsive skyrmion-edge interactions can induce such an edge-pinning effect for skyrmions.

Highlights

When magnetic skyrmions are moved via currents, they do not strictly travel along the path of the current, instead their motion gains a transverse component
One limitation that potential skyrmion applications may face is the occurrence of the skyrmion Hall effect (SkHE), which arises due to the topological nature of the skyrmions and drives them towards the edge of their hosting material when they are moved via currents[28,29,30]
We find that the Co/Fe bilayer has an immediate effect on the spin spiral ground state, stabilizes skyrmions and target states at zero field, and gives rise to skyrmions pinned to the Pd/Fe island edge in applied magnetic fields

Summary

Introduction

When magnetic skyrmions are moved via currents, they do not strictly travel along the path of the current, instead their motion gains a transverse component This so-called skyrmion Hall effect can be detrimental in potential skyrmion devices because it drives skyrmions towards the edge of their hosting material where they face potential annihilation. 1234567890():,; Magnetic skyrmions are whirling spin textures with topological properties that make them robust against external perturbations They were first described theoretically[1,2] and later found experimentally in systems with broken structural inversion symmetry such as chiral magnets[3,4] or magnetic ultra-thin films[5,6]. This configuration is preferred over a parallel alignment to the island edge, because it avoids the formation of a ferromagnetically ordered island rim[48], and in this way allows the DMI energy to be further reduced by edge tilting effects[37,49]

Methods

Results

Conclusion