Magnetic reversal modes in cylindrical nanowires

TLDR

The study focuses on electrodeposited cylindrical nanowires of permalloy, nickel, iron, and cobalt, whose crystal structures are tuned by deposition parameters. The authors systematically simulate the demagnetization of cylindrical nanowires with varying crystalline structures. Micromagnetic simulations were employed to calculate coercivity, remanence, angular dependence, and reversal modes as functions of diameter, exchange correlation length, and anisotropy, and to compare these results with experimental data and magnetic force microscopy images. The results show that crystallographic structure dictates whether magnetization reverses via transverse or vortex domain walls, with vortex structures spanning the entire wire, and the derived coercivity, remanence, and reversal mode diagrams agree with experimental observations.

Abstract

We perform a systematic study based on micromagnetic simulations of the demagnetization process for cylindrical nanowires with different crystalline structure. These simulations correspond to the most commonly reported electrodeposited nanowires, based on permalloy, nickel, iron and cobalt, with crystal structure tailored by electrodeposition parameters. The dependence of coercivity and remanence on the nanowire diameter, the angular dependence of coercivity and the corresponding reversal modes are calculated and discussed. Extensive comparison of the obtained coercive field value with available experimental data is presented. Depending on the crystallographic structure, the nanowires reverse magnetization by transverse or vortex domain walls and can exhibit the vortex structure along the whole nanowire length. The state diagrams for reversal modes in different materials as a function of the exchange correlation length, nanowire diameter and the anisotropy direction are presented. Magnetic force microscopy images corresponding to different structures are also evaluated by the micromagnetic simulations.