Time-resolved photoemission of Sr2IrO4

We investigate the temporal evolution of electronic states in strontium iridate Sr2IrO4. The time-resolved photoemission spectra of the intrinsic, electron-doped, and hole-doped samples are monitored in identical experimental conditions. Our data on the intrinsic and electron-doped samples, show that doublon-holon pairs relax near to the chemical potential on a time scale shorter than 70 fs. The subsequent cooling of low-energy excitations takes place in two steps: a rapid dynamics of ≅120 fs is followed by a slower decay of ≅1 ps. The reported time scales endorse the analogies between Sr2IrO4 and copper oxides.