Photoemission signatures of nonequilibrium carrier dynamics from first principles
Fabio Caruso, Dino Novko, Claudia Draxl
Abstract
Time- and angle-resolved photoemission spectroscopy (tr-ARPES) constitutes a powerful tool to inspect the dynamics and thermalization of hot carriers. The identification of the processes that drive the dynamics, however, is challenging even for the simplest systems owing to the coexistence of several relaxation mechanisms. Here, we devise a Green's function formalism for predicting the tr-ARPES spectral function of metals and establish the origin of carrier thermalization. The predictive power of this approach is demonstrated by an excellent agreement with experiments for graphene over timescales ranging from a few tens of femtoseconds up to several picoseconds. Our work provides compelling evidence of a nonequilibrium dynamics dominated by the establishment of a hot-phonon regime.