First-principles study of superconducting heterostructures
Prof. Kyungwha Park
Physics, Virginia Tech
Topological superconductivity has emerged a promising platform for fault-tolerant quantum computing using braiding of Majorana modes. Due to the rarity of intrinsic topological superconductors, heterostructures involving conventional superconductors have been proposed to realize topological superconductivity. Good candidates are proximity-induced three-dimensional topological insulator (TI) films overlaid on s-wave superconductors, and ferromagnetic atomic chains or semiconducting nanowires at s-wave superconducting (SC) surfaces. Despite extensive efforts, unambiguous experimental verification of Majorana zero modes remains elusive due to effects of interfaces and inherent disorder. First-principles methods are good for studying these effects. In this talk, I will present first-principles studies of two heterostructures: (i) TI Bi2Se3 films on SC PdTe; (ii) magnetic impurities on SC Pb. In the first system, I will discuss the proximity-induced SC gap features, quasiparticle spectra, and effective TI pairing potential as a function of film thickness and chemical potential, by solving the Dirac-Bogoliubov-de Gennes (DBdG) equations within the screened Korringa-Kohn-Rostoker method in the framework of density-functional theory. In the second system, I will present characteristics of in-gap quasiparticle excitations (i.e., Yu-Shiba-Rusinov states) arising from magnetic impurities (Fe, Co, Mn) at the surface of SC Pb including the band structure of Pb and 3d orbitals of the impurities, by combining the DBdG solver with the embedded-cluster Green’s function method. Our results will be compared with experiments and model Hamiltonian studies.
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