Zero-field deterministic all-optical writing and annihilation of nanometer-scale skyrmion bubbles

Abstract

Skyrmions are highly stable chiral magnetic spin textures with non-trivial topology. They can act as quasi-particles that can be generated, manipulated and annihilated, and hold promise for future memory and logic devices. As of now, all-optical stochastic nucleation of skyrmion ensembles, mostly in small applied magnetic fields, has been shown. However, to research their true potential, the ability to selectively toggle switch individual single skyrmions would be highly beneficial. In this paper, we demonstrate the field-free optical control of single stable skyrmions via single femtosecond laser pulses with diameters down to 175 nm, containing a fixed chirality. By engineering ferrimagnetic Co/Gd-based multilayers, we resolve the competition between deterministic and stochastic processes, and thereby overcome the challenge of optically writing and annihilating sub-micron skyrmions on demand. Our work is envisioned to fuel applications of skyrmion-based applications and opens up further endeavors in research related to the behaviour of more complicated skyrmion-based textures.