Spin-polarised current manipulation of Bloch points

Recently, it was demonstrated that confined helimagnetic nanostructures, composed of grains of different chirality (and consequently, a different sign of Dzyaloshinskii-Moriya energy constant), can host stable Bloch points [1]. In this work, using micromagnetic simulations, we explore if those magnetisation states can be manipulated using spin-polarised currents. We start by showing that a zero-field stable Bloch point emerges not only in thin-film disk samples [1] but also in an extensive range of planar geometries, including nanostrips. By applying an in-plane spin-polarised current, we demonstrate that Bloch points, in a planar nanostructure, can be moved in an arbitrary in-plane direction. Finally, by applying a spin-polarised current out-of-plane, we were able to switch the type of Bloch point between head-to-head and tail-to-tail states. Our demonstration of the ability to manipulate Bloch points in planar samples, apart from being of interest in fundamental physics, suggests the possible use of Bloch points in future spintronic devices.

[1] Beg et al. Scientific Reports 5, 17137 (2015).