• Open Access

Chiral Dirac superconductors: Second-order and boundary-obstructed topology

Apoorv Tiwari, Ammar Jahin, and Yuxuan Wang
Phys. Rev. Research 2, 043300 – Published 1 December 2020

Abstract

We analyze the topological properties of a chiral p+ip superconductor for a two-dimensional metal and semimetal with four Dirac points. Such a system has been proposed to realize second-order topological superconductivity and host corner Majorana modes. We show that with an additional C4 rotational symmetry, the system is in an intrinsic higher-order topological superconductor phase, and with a lower C2 symmetry, is in a boundary-obstructed topological superconductor phase. The boundary topological obstruction is protected by a bulk Wannier gap. However, we show that the well-known nested Wilson loop is in general unquantized despite the particle-hole symmetry, and thus fails as a topological invariant. Instead, we show that the higher-order topology and boundary-obstructed topology can be characterized using an alternative defect classification approach, in which the corners of a finite sample are treated as a defect of a space-filling Hamiltonian. We establish “Dirac+(p+ip)” as a sufficient condition for second-order topological superconductivity.

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  • Received 15 June 2020
  • Revised 17 October 2020
  • Accepted 20 October 2020

DOI:https://doi.org/10.1103/PhysRevResearch.2.043300

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Apoorv Tiwari1,2, Ammar Jahin3, and Yuxuan Wang3

  • 1Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
  • 2Condensed Matter Theory Group, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
  • 3Department of Physics, University of Florida, Gainesville, Florida 32601, USA

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Vol. 2, Iss. 4 — December - December 2020

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