Topological Insulator-Superconductor Heterostructures and Devices
Lin Li, IQC
A 3D topological insulator (TI) has a fully gapped insulating bulk state but a conducting surface. Such conducting “surface” states are formed with helical Dirac fermions, with spin-momentum strictly locked by spin-orbital coupling. When coupled to a conventional s-wave superconductor (S), the surface state behaves just like the desired p-wave superconductor. It has been predicted that Majorana zero-modes obeying non-Abelian statistics can appear in such a system. Braiding operations on the Majorana zero-modes can realize topological quantum computing. Therefore, it has boosted extensive interest in the topological insulator-superconductor (TI-S) heterostructures.
High quality TI-S heterostructures on wafer size scale are demanded for both fundamental studies as well as applications in the future. We explored molecular beam epitaxy (MBE) growth of TI-S bilayer heterostructures by depositing 3D topological insulator (Bi1-xSbx)2Te3 (BST) on two superconductors including Nb and MgB2. In addition, by capping another layer of Nb on top of the bilayer heterostructures and proceeding to fabrication, we achieved vertical S-TI-S junctions that have seldom been studied. In this talk, characterization results of the thin film heterostructures and transport measurement on the S-TI-S junctions will be presented.
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