Magnetostatic interaction between Bloch Point nanospheres

TL;DR

This paper analytically investigates the magnetostatic field of a Bloch Point in a nanosphere, revealing quadrupolar fields and complex interactions that depend on orientation and distance, advancing understanding of topological magnetic textures.

Contribution

It provides the first analytical calculation of the magnetostatic field of a Bloch Point in a nanosphere, showing quadrupolar nature and complex interaction behaviors.

Findings

BPs generate quadrupolar magnetic fields.

Interaction varies with orientation, being attractive or repulsive.

Interaction behavior exceeds simple topological charge effects.

Abstract

Three-dimensional topological textures have become a topic of intense interest in recent years. Through analytical calculations, this work determines the magnetostatic field produced by a Bloch Point (BP) singularity confined in a magnetic nanosphere. It is observed that BPs hosted in a nanosphere generate magnetic fields with quadrupolar nature. This finding is interesting because it shows the possibility of obtaining quadrupole magnetic fields with just one magnetic particle, unlike other propositions considering arrays of magnetic elements to generate this kind of field. The obtained magnetostatic field allows us to determine the interaction between two BPs as a function of the relative orientation of their polarities and the distance between them. It is shown that depending on the rotation of one BP related to the other, the magnetostatic interaction varies in strength and character, being attractive or repulsive. The obtained results reveal that the BP interaction has a complex behavior beyond topological charge-mediated interaction.