Tomasch Oscillations As Above-Gap Signature of Topological Superconductivity

The identification of topological superconductors usually involves searching for in -gap modes that are protected by topology. However, in current experimental settings, the smoking -gun evidence of these ingap modes is still lacking. In this Letter, we propose to support the distinction between two-dimensional conventional s -wave and topological p -wave superconductors by above -gap transport signatures. Our method utilizes the emergence of Tomasch oscillations of quasiparticles in a junction consisting of a superconductor sandwiched between two metallic leads. We demonstrate that the behavior of the oscillations in conductance as a function of the interface barriers provides a distinctive signature for s -wave and p -wave superconductors. Specifically, the oscillations become weaker as the barrier strength increases in s -wave superconductors, while they become more pronounced in p -wave superconductors, which we prove to be a direct manifestation of the pairing symmetries. Our method can serve as a complimentary probe for identifying some classes of topological superconductors through the above -gap transport.