Disentangling carrier scattering mechanisms in the high-purity metal KCo2As2 using time and angle resolved photoemission spectroscopy

We investigate single-particle lifetimes and photoexcited carrier relaxation times in KCo₂As₂ using time and angle resolved photoemission spectroscopy (tr-ARPES). KCo₂As₂ is a high-purity metal that is isostructural to iron pnictide superconductors, but does not display any magnetism or superconductivity. It is not clear whether scattering channels beyond electron-phonon coupling play a significant role in this compound. To determine the dominant scattering channel, we extract the energy and momentum resolved population lifetimes of carriers after the system is excited with an infrared pump pulse. We will compare these nonequilibrium lifetimes to single-particle lifetimes extracted from equilibrium photoemission to highlight KCo₂As₂ as a model system for disentangling various scattering mechanisms in clean metals.