# Current-driven skyrmion expulsion from magnetic nanostrips

## TL;DR

This paper investigates how current-driven skyrmions are expelled from magnetic nanostrips, analyzing the threshold current density and the influence of magnetic parameters through simulations and models.

## Contribution

It provides a detailed analysis of the factors affecting skyrmion expulsion, including the critical boundary force and magnetic parameters, offering insights into skyrmion stability in devices.

## Key findings

- Critical boundary force decreases with increasing exchange stiffness and anisotropy.
- Critical boundary force increases with Dzyaloshinskii-Moriya interaction and saturation magnetization.
- The stability of skyrmions is related to the scaled Dzyaloshinskii-Moriya-interaction parameter.

## Abstract

We study the current-driven skyrmion expulsion from magnetic nanostrips using micromagnetic simulations and analytic calculations. We explore the threshold current density for the skyrmion expulsion, and show that this threshold is determined by the critical boundary force as well as the spin-torque parameters. We also find the dependence of the critical boundary force on the magnetic parameters; the critical boundary force decreases with increasing the exchange stiffness and perpendicular anisotropy constants, while it increases with increasing Dzyaloshinskii-Moriya interaction and saturation magnetization constants. Using a simple model describing the skyrmion and locally-tilted edge magnetization, we reveal the underlying physics of the dependence of the critical boundary force on the magnetic parameters based on the relation between the scaled Dzyaloshinskii-Moriya-interaction parameter and the critical boundary force. This work provides a fundamental understanding of the skyrmion expulsion and the interaction between the skymion and boundaries of devices and shows that the stability of the skyrmion in devices can be related to the scaled Dzyaloshinskii-Moriya-interaction parameter of magnetic materials.