Momentum-dependent electron dynamics in a 2D aperiodic potential

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The field of electronic structure and electron dynamics of long-range ordered aperiodic systems is still in its infancy. In strong contrast to the well-studied electron dynamics in 2D and 3D periodic crystals, the absence of translational symmetry within the aperiodic potentials of quasicrystals is incompatible to the traditional picture of band structure and the delocalized Bloch states. In this context, our Taiwan-German project focusses on electrons in image potential states at the surface of dodecagonal oxide quasicrystals. It combines the advancement of 2D quasicrystal growth and the time- and momentum-resolved two-photon photoelectron spectroscopy. For dodecagonal oxide quasicrystals derived from BaTiO3 and SrTiO3 thin films grown on metallic substrates, image potential states are ideally accessible. For this textbook electron system, the impact of the aperiodic 2D structure on the energy-momentum dispersion of electrons and their femtosecond dynamics will be studied. Results for aperiodic potentials of different fundamental length and strength allow for a systematic comparison of induced modifications.