Ultrafast electron dynamics upon above band-gap excitation in epitaxial LaFeO3(001) thin films

Here you find all data for the paper.Strong electron correlations in perovskite oxides give rise to rich and often unexpected electronic phenomena. In this study, we present a comprehensive surface-science investigation of epitaxial thin films of the chargetransfer insulator LaFeO3(001). The characterization includes low-energy electron diffraction (LEED), high-resolution electron energy loss spectroscopy (HREELS), and photoemission spectroscopy. We map both the occupied and unoccupied electronic states using two-photon photoemission (2PPE) spectroscopy. Furthermore, we probe electron dynamics through an ultravioletultraviolet (UV-UV) pump-probe experiment, exciting electrons from hybridized O 2p/Fe 3d states to Fe minority-spin states above the band gap. Our results reveal three distinct unoccupied states, which we assign to Fe t 2g↓ , Fe e g↓ , and La 5d orbitals. Notably, the conduction band minimum exhibits a biexponential decay with time constants of 39 fs and 1100 fs, suggesting the presence of two independent decay pathways.