Map of metastable states for thin circular magnetic nano-cylinders

TL;DR

This paper maps the metastable magnetic states in thin circular nano-cylinders, revealing how shape and size influence static and dynamic properties, and identifies conditions for stable vortex states at zero field.

Contribution

It provides the first detailed map of metastable states in nano-cylindrical ferromagnetic islands near the exchange length, clarifying their stability and potential for device applications.

Findings

Identified the region of metastability for 'C'-type magnetic states.

Proved these states are genuine, not due to imperfections.

Outlined how to create the smallest particles with stable vortex states at zero field.

Abstract

Nano-magnetic systems of artificially shaped ferromagnetic islands, recently became a popular subject due to their current and potential applications in spintronics, magneto-photonics and superconductivity. When the island size is close to the exchange length of magnetic material (around 15 nm), its magnetic structure becomes markedly different. It determines both static and dynamic magnetic properties of elements, but strongly depends on their shape and size. Here we map this dependence for circular cylindrical islands of a few exchange lengths in size. We outline the region of metastability of "C"-type magnetic states, proving that they are indeed genuine and not a result of pinning on particle imperfections. A way to create the smallest particles with guaranteed magnetic vortex state at zero field becomes evident. It is expected that the map will help focus the efforts in planning of experiments and devices.