Magnetic topological insulators for robust Majorana bound states

• Applicants: Kristof Moors, Ph.D.; Professor Dr. Thomas Schäpers; Dr. Peter Schüffelgen
• Subject Area: Experimental Condensed Matter Physics ; Theoretical Condensed Matter Physics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 491798118

We propose to study the interplay between magnetism, band topology, and superconductivity with the aim of realizing robust topological states as future building blocks for quantum computation. Our project will combine experiments, materials simulations, and solid-state theory in order to study Majorana bound states based on magnetic topological insulators (MTIs) with proximity-induced superconductivity. The unique experimental platform available within this consortium as well as its theoretical know-how are ideally suited to address this challenge. On the experimental side, we will construct MTI nanostructures in situ in different geometries, e.g., as nanowires, junctions, or interferometers. Magnetotransport measurements will allow us a detailed characterization of the devices and their topological properties in the normal-conducting state. Next, we will apply superconducting leads for studying proximity-induced superconductivity and Josephson junctions based on MTIs. This finally will make it possible to create and detect Majorana bound states based on MTIs. The techniques used by our theory and simulation cluster will allow multiscale modelling of nanostructure-based devices and will closely accompany the experimental efforts. A constant feedback loop between experiments and theory will help us optimize device geometries and materials. While bulk MTIs have been investigated in detail, their nanostructures still leave open many fundamental questions. This project will therefore lead to important new insights, both in theory and experiment, about MTIs. The latter, in turn, will lead us to the ultimate goal of our project, which is to unambiguously identify Majorana bound states in MTI nanowires, and to pave the way for their future use in topological quantum computation.

• DFG Programme: Research Grants
• International Connection: France, Luxembourg, Spain, United Kingdom
• Cooperation Partners: Dr. Malcolm Connolly; Professor Dr. Thomas L. Schmidt; Dr. Llorenç Serra Crespí