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O: Fachverband Oberflächenphysik
O 38: Ultrafast electron dynamics at surface and interfaces II
O 38.3: Vortrag
Dienstag, 10. März 2026, 11:00–11:15, TRE/MATH
Ultrafast electron dynamics in charge-transfer insulators LaFeO3(001) and BiFeO3(001) — •Friederike Wührl, Antonia Rieche, Anne Oelschläger, Kathrin Dörr, and Wolf Widdra — MLU Halle-Wittenberg
The electron dynamics in strongly correlated systems, where electron-electron correlation leads to band gap opening, are highly unexplored. One example is the prototypical charge transfer insulator NiO, which shows a remarkable short lifetime of <10 fs at the conduction band minimum, relaxing in a many-body in-gap state, which couples to the antiferromagnetic spin system [1]. Here we are extending our time-resolved studies to the unoccupied states of epitaxial antiferromagnetic LaFeO3(001) and ferroelectric BiFeO3(001) thin films grown on SrRuO3/DyScO3(001) substrates. We use two-photon photoemission in a UV-UV pump-probe experiment, exciting electrons across the band gap, which opens between strongly hybridized oxygen 2p/Fe 3d and Fe minority states for both perovskites. We find in both sytems a broad state at ∼ 1.3 eV above EF with a short lifetime of 20 fs, whereas the conduction band minimum shows a multiexponential decay with timescales in the femtosecond to picosecond range. The different decay channels show an energy dependent increase of lifetimes towards the Fermi level. Comparing BiFeO3 and LaFeO3, the decay channels differ solely in their amplitudes, with a higher probability for the fast decay channel in LaFeO3.
[1] Gillmeister et al. Nat. Commun. 11, 4095 (2020).
Keywords: 2PPE; time-resolved; LaFeO$_3$; BiFeO$_3$; charge-transfer insulator