Hopfions in chiral magnets

TL;DR

This paper demonstrates the existence of stable magnetic Hopfions in chiral magnets through numerical simulations and provides an analytic approximation, also proposing a method to create them from Skyrmions.

Contribution

It presents the first numerical evidence of stable Hopfions in chiral magnets and offers an explicit analytic expression for their structure.

Findings

Stable Hopfions exist in chiral magnet nanocylinders.

An explicit analytic approximation matches numerical results.

A proposed method to generate Hopfions from Skyrmions.

Abstract

A magnetic Hopfion is a three-dimensional topological soliton that consists of a closed loop of a twisted magnetic Skyrmion string. The results of numerical simulations are presented that demonstrate the existence of a stable Hopfion in a nanocylinder of a chiral magnet and an explicit analytic expression is shown to provide a reasonable approximation to the numerically computed Hopfion. A mechanism is suggested to create the Hopfion from a target Skyrmion by introducing an interfacial perpendicular magnetic anisotropy.