Abstract
We analyze the topological properties of a chiral 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 rotational symmetry, the system is in an intrinsic higher-order topological superconductor phase, and with a lower 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 “” as a sufficient condition for second-order topological superconductivity.
- 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