Revealing Hund’s multiplets in Mott insulators under strong electric fields

We investigate the strong-field dynamics of a paramagnetic two-band Mott insulator using real-time dynamical mean-field theory. We demonstrate that strong electric fields can lead to a transient localization of electrons. This nonequilibrium quantum effect allows us to reveal specific signatures of local correlations in the time-resolved photoemission spectrum. In particular, we demonstrate that the localization can be strong enough to produce atomiclike spin multiplets determined by the Hund's coupling J, and thus provide a way of measuring J inside the solid. Our simulation also fully incorporates nonlinear field-induced tunneling processes, which would lead to a dielectric breakdown in the steady state limit. A careful analysis of these processes, however, shows that they remain weak enough and do not prevent the measurement of the transiently localized spectra