Metastability in individual magnetic vortices

TL;DR

This paper demonstrates how high-temperature nanoSQUIDs can characterize individual magnetic vortices in nanoparticles, revealing metastable states and methods to reduce metastability for improved control in applications.

Contribution

The study introduces nanoSQUID-based measurement techniques to analyze metastability in magnetic vortices and proposes asymmetry as a way to reduce metastable configurations.

Findings

Detection of multiple metastable vortex states.

Metastability can be minimized by introducing asymmetry.

NanoSQUIDs enable detailed characterization of magnetic vortices.

Abstract

Magnetic nanoparticles play a crucial role in different fields such as biomedicine or information and quantum technologies. These applications require nanoparticles with a single, well-defined energy minimum, free of metastable states, and characterized by narrow switching field distributions. Here, we demonstrate that high-transition-temperature nanoSQUIDs can be successfully applied to the characterization of individual nanodiscs hosting magnetic vortices. We present measurements performed under varying temperature and external magnetic field, revealing signatures of ubiquitous, multiple metastable configurations. We also demonstrate that metastability can be reduced by introducing an intended asymmetry. NanoSQUID measurements can be applied to optimize the fabrication of on-demand spin-texture states, such as degenerated vortices or particles with fixed circulation and deterministic and narrow switching probabilities.