Crossover between two different magnetization reversal modes in arrays of iron oxide nanotubes

TL;DR

This study theoretically investigates magnetization reversal modes in iron oxide nanotube arrays, revealing a crossover from vortex to transverse reversal modes depending on wall thickness, with implications for magnetic device design.

Contribution

It identifies and characterizes a crossover between two magnetization reversal modes in nanotube arrays based on wall thickness, supported by theoretical calculations and agreement with experiments.

Findings

Reversal mode switches from vortex to transverse at 13 nm wall thickness.

Magnetostatic interactions reduce coercive field in arrays.

Crossover phenomenon is predicted to be general across similar systems.

Abstract

The magnetization reversal in ordered arrays of iron oxide nanotubes of 50 nm outer diameter grown by atomic layer deposition is investigated theoretically as a function of the tube wall thickness, $d_{w}$. In thin tubes ($d_{w}<13$ nm) the reversal of magnetization is achieved by the propagation of a vortex domain boundary, while in thick tubes ($d_{w}>13$ nm) the reversal is driven by the propagation of a transverse domain boundary. Magnetostatic interactions between the tubes are responsible for a decrease of the coercive field in the array. Our calculations are in agreement with recently reported experimental results. We predict that the crossover between the vortex and transverse modes of magnetization reversal is a general phenomenon on the length scale considered.