Critical Temperature of a Superconductor/Ferromagnet Nanostructure near a Magnetic Skyrmion

Contact between a superconductor and a chiral ferromagnet containing complex magnetic structures (helical or conical texture, skyrmion, and chiral float) has been considered. The case of a single skyrmion has been studied more thoroughly. The influence of these magnetic inhomogeneities on the critical temperature becomes significant only for nanoscale spin structures (about 100 nm or smaller). Skyrmion lattices and single skyrmions of such sizes have recently been observed in experiments with thin magnetic layers. Within the proximity effect theory in the dirty limit, an approximate approach has been proposed to calculate the critical temperature in these systems. Great influence of nanoscale spin vortices on the critical temperature, in combination with topological stability and a low current density that is necessary for their motion, makes it possible to use these systems as efficient superconducting spin valves.