Magnetic domain control and its dependence on aspect ratio and thickness in Ni nanolayer patterns for nanowire spintronic devices

Abstract

We investigate the aspect ratio and thickness dependence of magnetic domain formation in multiple types of ferromagnetic Ni nanolayer electrode patterns. Controlling magnetic domains is critical for spintronic devices using a group IV semiconductor, e.g. Si and Ge, nanowire as the electrodes with magnetic tunnel junction require parallel and anti-parallel magnetization configurations. Single magnetic domains are obtained in the Ni nanolayer electrode patterns on SiO2/Si substrate with an aspect ratio of 20 and a thickness of 40 nm even under the as-deposition condition, while other electrode patterns are mostly showing multiple magnetic domains. The results obtained by magnetic force microscopy also show that the magnetization switching is observed in the electrode pattern with a single magnetic domain. The results in this study show that the suitable design of the dimensions of nanolayer patterns is key to constructing a single magnetic domain in a ferromagnetic electrode for nanowire spintronic devices.