Moiré Surface States and Enhanced Superconductivity in Topological Insulators

Taige Wang; Noah F. Q. Yuan; Liang Fu

doi:10.1103/PhysRevX.11.021024

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Moiré Surface States and Enhanced Superconductivity in Topological Insulators

Taige Wang, Noah F. Q. Yuan, Liang Fu

DOI 10.1103/PhysRevX.11.021024 · Physical Review X

T1

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Abstract

Recently, moiré superlattices have been found on the surface of topological insulators due to the rotational misalignment of topmost layers. In this work, we study the effects of moiré superlattices on the topological surface states using a continuum model of Dirac electrons moving in a periodic potential. Unlike twisted bilayer graphene, moiré surface states cannot host isolated bands due to their topological nature. Instead, we find (high-order) van Hove singularities (VHS) in the moiré band structure that give rise to divergent density of states (DOS) and enhance interaction effects. Because of spin-momentum locking in moiré surface states, possible interaction channels are limited. In the presence of phonon mediated attraction, superconductivity is strongly enhanced by the power-law divergent DOS at high-order VHS. The transition temperature Tc exhibits a power-law dependence on the retarded electron-phonon interaction strength λ*. This enhancement is found to be robust under various perturbations from the high-order VHS.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Bi2Te3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown