Three-dimensional structure and formation mechanism of biskyrmions in uniaxial ferromagnets

TL;DR

This study uses micromagnetic simulations to reveal the three-dimensional structure and formation mechanism of magnetic biskyrmions in uniaxial ferromagnetic films, clarifying their existence and transformation processes.

Contribution

It demonstrates the existence of biskyrmions in uniaxial ferromagnets and uncovers their 3D structure and formation mechanism through simulations.

Findings

Biskyrmions share a unified 3D structure with bubbles.

Edge effects can transform bubbles into biskyrmions.

Biskyrmions form in confined geometries under zero field.

Abstract

Magnetic biskyrmions are observed in experiments but their existences are still under debate. In this work, we present the existence of biskyrmions in a magnetic film with tilted uniaxial anisotropy via micromagnetic simulations. We find biskyrmions and bubbles share a unified three-dimensional structure, in which the relative position of two intrinsic Bloch points dominates the two-dimensional topological property in the film middle. The film edge can drive Bloch points and transform bubbles into biskyrmions via the demagnetizing field. This mechanism is found in the formation process of biskyrmions in confined geometry under zero field. Our work clarifies the structure and formation mechanism of biskyrmions, emphasizing the three-dimensional aspect of skyrmion-related nanostructures.