piwik-script

Intern
    SFB 1170

    C02

    Surface studies of topological superconductors

    Summary

    Topological and unconventional superconductivity (SC) are focal topics of this SFB 1170. Yet, published results predominantly consist of theoretical work; successful reports in the scientific literature are rare and heavily disputed. For example, it has been controversially discussed whether Majorana fermions reported for magnetic chains on strongly spin-orbit–coupled SC exist or rather represent non-topological Shiba states. In this project we will pursue customized approaches to investigate (i) superconducting-doped topological insulators and (ii) strongly spin-orbit–coupled superconductor-ferromagnet hybrids to study unconventional superconductivity. In preliminary work performed towards part (i) of this project, we studied the structural and electronic properties of two potential topological SC, i.e., Nb- and Tl-doped topological insulators with tetradymite structure, which both turned out to be normal conducting at the surface, potentially due to n-type surface band bending effects. Within this project, we will p-dope these surfaces by appropriate adsorbates, such as C60, and investigate alternate topological SCs, such as Cu- or Sr-doped Bi2Se3. Furthermore, (ii) we will study two-dimensional islands and atom-by-atom–assembled atomic chains on strongly spin-orbit–coupled superconductors by spin-polarized STM and STS. Towards this goal we will utilize substrate materials which combine a high critical temperature with suitability for atomic resolution, such as Nb(110). We will use our expertise in surface science, thin-film epitaxy, and atomic manipulation together with an improved energy resolution we will achieve by a new 3He-cooled cryostat requested here to overcome existing limitations and test theoretical proposals with high spatial and energy resolution.