Switching of chiral magnetic skyrmions by picosecond magnetic field pulses via transient topological states

TL;DR

This paper demonstrates how short magnetic field pulses can reliably switch chiral magnetic skyrmions between states of opposite polarity at GHz rates, revealing complex topological transition pathways.

Contribution

It introduces a method for controlled skyrmion switching using magnetic field pulses and analyzes the underlying topological transition mechanisms.

Findings

Short magnetic field pulses can induce skyrmion switching at GHz rates.

A range of material parameters supports coexistence of degenerate skyrmions.

Complex transition pathways involve meron pairs and achiral skyrmions.

Abstract

Magnetic chiral skyrmions are vortex like spin structures that appear as stable or meta-stable states in magnetic materials due to the interplay between the symmetric and antisymmetric exchange interactions, applied magnetic field and/or uniaxial anisotropy. Their small size and internal stability make them prospective objects for data storage but for this, the controlled switching between skyrmion states of opposite polarity and topological charge is essential. Here we present a study of magnetic skyrmion switching by an applied magnetic field pulse based on a discrete model of classical spins and atomistic spin dynamics. We found a finite range of coupling parameters corresponding to the coexistence of two degenerate isolated skyrmions characterized by mutually inverted spin structures with opposite polarity and topological charge. We demonstrate how for a wide range of material parameters a short inclined magnetic field pulse can initiate the reliable switching between these states at GHz rates. Detailed analysis of the switching mechanism revealed the complex path of the system accompanied with the excitation of a chiral-achiral meron pair and the formation of an achiral skyrmion.