Bulk Bogoliubov Fermi arcs in non-Hermitian superconducting systems

TL;DR

This paper introduces bulk Bogoliubov Fermi arcs in non-Hermitian superconductors, arising from exceptional points and topologically protected zero-energy lines, which are tunable and experimentally observable.

Contribution

It reveals the existence of bulk Bogoliubov Fermi arcs in non-Hermitian superconducting systems, linking exceptional points to topological zero-energy lines.

Findings

Exceptional points occur under Zeeman field in non-Hermitian superconductors.

Bulk Fermi arcs are topologically protected and highly tunable.

Large spectral signatures make these arcs experimentally detectable.

Abstract

We consider a non-Hermitian superconducting system by coupling a conventional superconductor to a ferromagnet lead and demonstrate the emergence of exceptional points when an external Zeeman field is applied. We discover that, depending on the non-Hermiticity and the Zeeman field, the exceptional points mark the ends of lines with zero real energy, thus giving rise to topologically protected and highly tunable bulk Fermi arcs, which we coin bulk Bogoliubov Fermi arcs due to their superconducting nature. We show that these bulk Bogoliubov Fermi arcs are the non-Hermitian counterparts of the Hermitian topological phase transition but are much more prevalent and also experimentally detectable through large spectral signatures.