Document Type

Article

Department/Program

Physics

Journal Title

Physical Review B

Pub Date

7-2019

Volume

100

Issue

2

Abstract

We identify three-dimensional higher-order superconductors characterized by the coexistence of one-dimensional Majorana hinge states and gapless surface states. We show how such superconductors can be obtained starting from the model of a spinful quadrupolar semimetal with two orbitals and adding an s-wave superconducting pairing term. By considering all the possible s-wave pairings satisfying Fermi-Dirac statistics we obtain six different superconducting models. We find that for two of these models a flat band of hinge Majorana states coexist with surface states, and that these models have a nonvanishing quadrupolelike topological invariant. Two of the other models, in the presence of a Zeeman term, exhibit helical and dispersive hinge states localized only at two of the four hinges. We find that these states are protected by combinations of rotation and mirror symmetries, and that the pair of corners exhibiting hinge states switches upon changing the sign of the Zeeman term. Furthermore, we show that these states can be localized to a single hinge with suitable perturbations. The remaining two models retain gapless bulk and surface states that spectroscopically obscure any possible hinge states.

DOI

https://doi.org/10.1103/PhysRevB.100.020509

Publisher Statement

This work is made available for educational and personal use only. Copyright is credited to the authors. Any other uses should be directed to the publisher.

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