Quantification of competing magnetic states and switching pathways in curved nanowires by direct dynamic imaging

TL;DR

This study introduces a dynamic imaging method to quantify and analyze competing magnetic states and switching pathways in curved nanowires, crucial for improving the reliability of spintronic devices.

Contribution

It presents a novel approach combining time-resolved microscopy and simulations to identify and quantify stochastic switching pathways and rare events in magnetic nanowires.

Findings

Identified multiple stable magnetic states and switching pathways.

Quantified the frequency and energy barriers of thermally activated state changes.

Revealed mechanisms behind domain wall chirality control.

Abstract

For viable applications, spintronic devices based e.g. on domain wall motion need to be highly reliable with stable magnetization states and highly reproducible switching pathways transforming one state to another. The existence of multiple stable states and switching pathways in a system is a definitive barrier for device operation, yet rare and stochastic events are difficult to detect and understand. We demonstrate an approach to quantify competing magnetic states and stochastic switching pathways based on time-resolved scanning electron microscopy with polarization analysis, applied to the technologically relevant control of vortex domain wall chirality via field and curvature in curved wires. While being a pump-probe technique, our analysis scheme nonetheless allows for the disentanglement of different occurring dynamic pathways and we can even identify the rare events leading to changes from one magnetization switching pathway to another pathway via temperature- and geometry-dependent measurements. The experimental imaging is supported by micromagnetic simulations to reveal the mechanisms responsible for the change of the pathway. Together the results allow us to explain the origin and details of the domain wall chirality control and to quantify the frequency and the associated energy barriers of thermally activated changes of the states and switching pathways.