Interaction of mesoscopic magnetic textures with superconductors

Abstract

Here we report a method to calculate the vortex and magnetization arrangement for a system of interacting superconductors and ferromagnets separated in space. The method is based on static London-Maxwell equations and the corresponding energy. Possible superconducting vortices are included in this system. Using this method we analyze screening currents in a superconducting film induced by magnetic textures in a thin magnetic film. We assume that the two films are parallel and positioned close to each to other, but interact exclusively via magnetic fields. We also consider possible vortices within this superconducting film and their interactions with magnetic texture. As an example of such magnetic texture we use a single magnetic dot with magnetization either perpendicular or parallel to the film. We derive a condition where spontaneous formation of one, two, or more vortices and antivortices is energetically favorable. We prove that, in the case of such a circular magnetic dot with perpendicular magnetization, when the vortex emerges in the superconducting film the normal component of magnetic field near the superconducting film changes sign outside of the dot range.