Stable skyrmion bundles at room temperature and zero magnetic field in a chiral magnet

TL;DR

This study demonstrates the creation of stable skyrmion bundles with high topological charge at room temperature and zero magnetic field in a chiral magnet, advancing topological spintronics applications.

Contribution

It reports the experimental realization of stable skyrmion bundles with high topological charge in a chiral magnet at ambient conditions, previously unachieved.

Findings

Achieved skyrmion bundles with Q up to 24 at room temperature and zero magnetic field.

Demonstrated field-driven annihilation of high-Q skyrmion bundles.

Validated experimental results with micromagnetic simulations showing skyrmion tubes encircled by fractional Hopfions.

Abstract

Topological spin textures are characterized by topological magnetic charges, Q, which govern their electromagnetic properties. Recent studies have achieved skyrmion bundles with arbitrary integer values of Q, opening possibilities for exploring topological spintronics based on Q. However, the realization of stable skyrmion bundles in chiral magnets at room temperature and zero magnetic field - the prerequisite for realistic device applications - has remained elusive. Here, through the combination of pulsed currents and reversed magnetic fields, we experimentally achieve skyrmion bundles with different integer Q values - reaching a maximum of 24 at above room temperature and zero magnetic field - in the chiral magnet Co8Zn10Mn2. We demonstrate the field-driven annihilation of high-Q bundles and present a phase diagram as a function of temperature and field. Our experimental findings are consistently corroborated by micromagnetic simulations, which reveal the nature of the skyrmion bundle as that of skyrmion tubes encircled by a fractional Hopfion.