Unhinging the Surfaces of Higher-Order Topological Insulators and Superconductors

Apoorv Tiwari; Ming-Hao Li; B. A. Bernevig; Titus Neupert; S. A. Parameswaran

doi:10.1103/PhysRevLett.124.046801

← Back to search

Unhinging the Surfaces of Higher-Order Topological Insulators and Superconductors

Apoorv Tiwari, Ming-Hao Li, B. A. Bernevig, Titus Neupert, S. A. Parameswaran

DOI 10.1103/PhysRevLett.124.046801 · Physical Review Letters

T1

Active bibliographic source — not scientific approval

Bibliographic access preserves source history; it does not approve extracted materials or validate reported claims. Review warnings on each occurrence separately.

Abstract

We show that the chiral Dirac and Majorana hinge modes in three-dimensional higher-order topological insulators (HOTIs) and superconductors (HOTSCs) can be gapped while preserving the protecting C2nT symmetry upon the introduction of non-Abelian surface topological order. In both cases, the topological order on a single side surface breaks time-reversal symmetry, but appears with its time-reversal conjugate on alternating sides in a C2nT preserving pattern. In the absence of the HOTI/HOTSC bulk, such a pattern necessarily involves gapless chiral modes on hinges between C2nT-conjugate domains. However, using a combination of K-matrix and anyon condensation arguments, we show that on the boundary of a 3D HOTI/HOTSC these topological orders are fully gapped and hence “anomalous.” Our results suggest that new patterns of surface and hinge states can be engineered by selectively introducing topological order only on specific surfaces.