Edge-mediated skyrmion chain and its collective dynamics in a confined geometry

TLDR

Magnetic skyrmions, topologically nontrivial vortex‑like structures, have opened new memory device concepts, and theory shows that chains of skyrmions in one‑dimensional nanostripes can encode information bits. This study reports the experimental observation of a skyrmion chain in FeGe nanostripes. High‑resolution Lorentz transmission electron microscopy was employed to image the skyrmion chain in FeGe nanostripes. Under magnetic fields, distorted edge spins in FeGe nanostripes evolve into individual skyrmions that form a chain at low fields and collectively migrate into the stripe interior at higher fields, a chain that persists even when the stripe width greatly exceeds a single skyrmion’s size, illustrating edge‑mediated skyrmion formation with potential device implications.

Abstract

The emergence of a topologically nontrivial vortex-like magnetic structure, the magnetic skyrmion, has launched new concepts for memory devices. Extensive studies have theoretically demonstrated the ability to encode information bits by using a chain of skyrmions in one-dimensional nanostripes. Here, we report experimental observation of the skyrmion chain in FeGe nanostripes by using high-resolution Lorentz transmission electron microscopy. Under an applied magnetic field, we observe that the helical ground states with distorted edge spins evolve into individual skyrmions, which assemble in the form of a chain at low field and move collectively into the interior of the nanostripes at elevated fields. Such a skyrmion chain survives even when the width of the nanostripe is much larger than the size of single skyrmion. This discovery demonstrates a way of skyrmion formation through the edge effect, and might, in the long term, shed light on potential applications.