Separated Edge-Soliton Meditated Dynamic Switching of Vortex Chirality and Polarity

TL;DR

This paper introduces a low-energy electrical method to switch both vortex chirality and polarity in magnetic nano-disks using edge soliton dynamics, with potential applications in spintronic devices.

Contribution

It presents a novel approach combining micromagnetic simulations and current-induced fields to control vortex states in nano-disks, enabling direct writing of any vortex configuration.

Findings

Efficient switching of vortex chirality and polarity in disks larger than 160 nm.

Switching process is size-dependent, with smaller disks switching both states simultaneously.

Critical current for switching can be as low as 3 x 10^6 A/cm^2.

Abstract

Magnetic vortices are characterized by the senses of in-plane magnetization chirality and by the polarity of the vortex core. The electrical control of vortex polarity and chirality is highly demanded not only for fundamental understanding on spin dynamics in nano-disks under different circumstances, but also for technological applications, such as magnetic non-volatile memories and spin torque oscillators for neuromorphic computing. Here we report a novel approach that enables one to electrically control both the vortex chirality and polarity with low energy consumption. Thorough micromagnetic simulations, we show that in thin nano-disks of diameter larger than 160 nm, with the presence of current-induced Oersted field, the dynamic transformation of the edge solitons is able to efficiently switch both vortex chirality and polarity with low current under certain circumstances. We then developed an approach to directly write any of the four vortex states by electrical current pulses from a random state. We further investigated the switching phase diagram as a function of disk diameters. The results show that the switching process is highly size-dependent. As disk diameter is smaller than 160 nm, the switch of VC chirality and polarity always takes place at the same time, resulting in an unchanged handedness before and after switch. Furthermore, the critical switch current can be as low as 3 x 10^6 A/cm^2 , indicating a possible way for low current switch of vortex chirality in small disks.