Moiré Surface States and Enhanced Superconductivity in Topological Insulators

Recently, moiré superlattices have been found on the surface of topological insulators due to rotational misalignment topmost layers. In this work, we study effects states using a continuum model Dirac electrons moving in periodic potential. Unlike twisted bilayer graphene, cannot host isolated bands their nature. Instead, find (high-order) van Hove singularities (VHS) band structure that give rise divergent density (DOS) and enhance interaction effects. Because spin-momentum locking states, possible channels are limited. presence phonon mediated attraction, superconductivity is strongly enhanced by power-law DOS at high-order VHS. The transition temperature Tc exhibits dependence retarded electron-phonon strength ?*. This enhancement be robust under various perturbations from VHS.1 MoreReceived 27 October 2020Revised 9 February 2021Accepted March 2021DOI:https://doi.org/10.1103/PhysRevX.11.021024Published American Physical Society terms Creative Commons Attribution 4.0 International license. Further distribution work must maintain attribution author(s) published article’s title, journal citation, DOI.Published SocietyPhysics Subject Headings (PhySH)Research AreasDensity statesElectron-phonon couplingSuperconductivitySurface statesTopological insulatorsvan singularityPhysical SystemsInterfacesSuperlatticesSurfacesVan der Waals systemsTechniquesBCS theoryRenormalizationk dot p methodCondensed Matter, Materials & Applied Physics