Two-electron photoemission spectroscopy as a probe of superconducting correlations and Debye energy

We demonstrate that the photoemission counting rate P⁽²⁾ measured in two electron photoemission spectroscopy (2e-ARPES) provides unprecedented insight into the nature of topological superconductivity. In particular, it allows us to detect induced superconducting spin-triplet correlations in a topological superconductor, and hence can be used to distinguish two recently proposed mechanisms for the topological superconductivity in FeSe_0.45Te_0.55. Moreover, we demonstrate P⁽²⁾ can be employed to detect topological phase transitions, as well as provide insight into the characteristic energy scale for superconducting pairing, the Debye energy.