Topological Synergy of Magnetism and Superconductivity

• Applicants: Professor Dr. Markus Garst; Professor Dr. Alexander Mirlin; Professor Dr. Alexander Shnirman
• Subject Area: Theoretical Condensed Matter Physics
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 445312953

This is a DFG-RSF cooperation project with Landau Institute for Theoretical Physics (Chernogolovka, Moscow region) in the framework of the call for joint German-Russian project proposals in the field of physics and mathematics. Cooperation with the Russian group, which includes world-leading experts in topology, spintronics, superconducting nanostructures and quantum coherence, and is lead by Prof. Dr. Yakov Fominov, is crucial for the success of the proposal.Topology plays a major role in condensed matter physics, including both magnetism and superconductivity. Magnetic systems give rise to emergent topological objects such as skyrmions. Physical properties and manipulation of skyrmions attract much attention, also in view of potential applications in information storage. In superconducting materials, vortices are basic topological objects which play a crucial role in electromagnetic response. More recently a very different manifestation of topology in superconductors was discovered. Specifically, topological superconductors that host topologically protected gapless surface excitations have been theoretically predicted and engineered in heterostructures. These surface modes have a character of Majorana fermions.They are characterized by non-Abelian statistics and can be used for topological quantum computing.In this project we plan to explore the synergy of magnetic and superconducting topologies in hybrid superconductor-ferromagent (SF) structures. The guiding theme of this project is the fact that topology in one constituent of a heterostructure (magnetic of electronic) induces new properties, including possibly a new topology, in another constituent.The proposal consists of four Work Packages (WP). In WP I we explore topological textures in helimagnets, which provide novel approaches to the generation and control of Majorana bound states without nano-engineering. WP II deals with interplay of skyrmions and vortices in SF heterostructures. WP III investigates SF structures on surfaces of 3D topological insulators. In these structures Majorana modes emerge at 1D SF boundaries and are expected to strongly influence the magnetic dynamics. Finally, WP IV deals with long range Josephson effect induced by interaction between supercurrent and topological magnetic textures in SFS junctions.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Science Foundation, until 3/2022
• Cooperation Partner: Professor Dr. Yakov Fominov, until 3/2022