Time-resolved imaging of \OE rsted field induced magnetization dynamics in cylindrical magnetic nanowires

TL;DR

This study uses time-resolved imaging to observe how Oersted fields influence magnetization dynamics in cylindrical nanowires, revealing domain tilting and domain wall breathing phenomena, advancing understanding in 3D spintronics.

Contribution

First direct imaging of magnetization response to Oersted fields in cylindrical nanowires, demonstrating domain tilting and domain wall breathing with a robust modeling approach.

Findings

Magnetization domains tilt towards the azimuthal Oersted field.

Domain walls exhibit breathing behavior under weak pulses.

The work provides a foundation for studying ultra-fast domain wall dynamics.

Abstract

Recent studies in three dimensional spintronics propose that the \OE rsted field plays a significant role in cylindrical nanowires. However, there is no direct report of its impact on magnetic textures. Here, we use time-resolved scanning transmission X-ray microscopy to image the dynamic response of magnetization in cylindrical Co$_{30}$Ni$_{70}$ nanowires subjected to nanosecond \OE rsted field pulses. We observe the tilting of longitudinally magnetized domains towards the azimuthal \OE rsted field direction and create a robust model to reproduce the differential magnetic contrasts and extract the angle of tilt. Further, we report the compression and expansion, or breathing, of a Bloch-point domain wall that occurs when weak pulses with opposite sign are applied. We expect that this work lays the foundation for and provides an incentive to further studying complex and fascinating magnetization dynamics in nanowires, especially the predicted ultra-fast domain wall motion and associated spin wave emissions.