Edge currents as a signature of flat bands in topological superconductors

Abstract

We study nondegenerate flat bands at the surfaces of noncentrosymmetric topological superconductors by exact diagonalization of Bogoliubov-de Gennes Hamiltonians. We show that these states are strongly spin polarized, and acquire a chiral dispersion when placed in contact with a ferromagnetic insulator. This chiral mode carries a large edge current which displays a singular dependence on the exchange-field strength. The contribution of other edge states to the current is comparably weak. We hence propose that the observation of the edge current can serve as a test of the presence of nondegenerate flat bands.

arXiv comment5 pages, 4 figures, plus supplemental material, published version

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• Topological Blount's theorem of odd-parity superconductors
• Inflated nodes and surface states in superconducting half-Heusler compounds
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