All-Optical Magnetothermoelastic Skyrmion Motion

It is predicted that magnetic skyrmions can be controllably moved on surfaces using a focused laser beam. Here an absorbed power of the order 1 mW, focused to a spot size of the order 1 mu m, results in a local temperature increase of around 50 K, and a local perpendicular strain of the order 10(-3) due to the thermoelastic effect. For positive magnetoelastic coupling this generates a strong attractive force on skyrmions due to the magnetoelastic effect. The resultant motion is dependent on forces due to (i) gradients in the local strain-induced magnetic anisotropy, (ii) temperature gradients resulting in magnetic parameter gradients due to their temperature dependences, especially local effective anisotropy gradients, and (iii) Magnus effect acting on objects with nonzero topological number. Using dynamical magnetothermoelastic modeling, it is predicted skyrmions can be moved with significant velocities (up to 80 m/s shown), both for ferromagnetic and antiferromagnetic skyrmions, even in the presence of surface roughness. This mechanism of controllably moving single skyrmions in any direction, as well as addressing multiple skyrmions in a lattice, offers an approach to constructing and studying skyrmionic devices with all-optical control.