Magnetization states and switching in narrow-gapped ferromagnetic nanorings

TL;DR

This study investigates how narrow gaps in ferromagnetic nanorings influence their magnetization states and switching behavior, combining simulations and microscopy to identify key parameters for potential storage device applications.

Contribution

It introduces the impact of gap shape and edge profile on switching fields in gapped nanorings, providing new insights for device control.

Findings

Gapped nanorings maintain vortex ground states.

Gap shape critically affects switching fields.

Magnetic force microscopy effectively probes vortex chirality.

Abstract

We study permalloy nanorings that are lithographically fabricated with narrow gaps that break the rotational symmetry of the ring while retaining the vortex ground state, using both micromagnetic simulations and magnetic force microscopy (MFM). The vortex chirality in these structures can be readily set with an in-plane magnetic field and easily probed by MFM due to the field associated with the gap, suggesting such rings for possible applications in storage technologies. We find that the gapped ring edge characteristics (i.e., edge profile and gap shape) are critical in determining the magnetization switching field, thus elucidating an essential parameter in the controls of devices that might incorporate such structures.