Direct Observation of Transverse and Vortex Metastable Magnetic Domains observed in Cylindrical Nanowires

TL;DR

This study experimentally observes and analyzes metastable transverse and vortex magnetic domains in cylindrical nanowires, revealing their coexistence and potential applications in sensing and recording technologies.

Contribution

First experimental observation of transverse magnetic domains in cylindrical nanowires alongside vortex domains, supported by microscopy and micromagnetic simulations.

Findings

Transverse and vortex domains coexist in nanowires.

Transverse domains generate larger surface stray fields.

Experimental results align with micromagnetic simulations.

Abstract

We present experimental evidence of metastable magnetic domains in cylindrical CoNi nanowires. Transverse (perpendicular) domains have been previously observed only in flat nanostrips. Here they are found together with more conventional vortex domains along the same cylindrical nanowire, denoting a bistable system with similar free energies. The surface and the inner magnetization distribution in both types of domains are analyzed by Photo-Emission Electron Microscopy (PEEM) with X-ray magnetic circular dichroism (XMCD) contrast, and hysteresis loop in individual nanowires are measured by Magneto-optical Kerr effect. These experimental data are understood and compared with complementary micromagnetic simulations. The transverse domain states are potentially more important for sensing and recording applications than commonly observed vortex domains since they create larger surface stray fields.