Topological superconductivity mediated by magnons of a skyrmion crystal.

Topological superconductors are associated with the appearance of Majorana modes. One mechanism to produce topological superconductors is to interface a conventional superconductor with a non-collinear magnetically ordered state like a skyrmion. In this work, we instead study a system where a skyrmion crystal is interfaced with a normal metal. Through interfacial exchange coupling, spin fluctuations (magnons) in the skyrmion crystal mediate an effective electron-electron interaction in the normal metal. We show that this yields topological superconductivity at the interface. The non-collinearity of the magnetic ground state is crucial in order to obtain this.