Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 37: Ultrafast electron dynamics at surface and interfaces – Poster (joint session O/TT)
TT 37.9: Poster
Tuesday, March 10, 2026, 14:00–16:00, P2
Image potential states of oxide quasicrytals — •Barbara Drobinski1, Friederike Wührl1, Richard Kraska1, Konrad Gillmeister1, Stefan Förster1, Cheng-Tien Chiang2, and Wolf Widdra1 — 1Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany — 2Institute of Atomic and Molecular Sciences , Academia Sinica, Taipeh, Taiwan
Quasicrystals are aperiodically ordered materials that lack translational symmetry. Their aperiodic potentials give rise to an infinitely dense set of Fourier components, which can induce gaps and mini-gaps in the electronic band structure. Here, we investigate this phenomenon for nearly free-electron-like image-potential surface states, where electrons propagate in front of the surface while experiencing the aperiodic potential. Using momentum-resolved two-photon photoemission, we determine both the electronic dispersion and relaxation dynamics of oxide quasicrystals (OQCs) based on Ba-Ti-O/Pt(111) [1] and Eu-Ti-O/Pt(111). The latter is obtained via Eu decoration of a Ti2O3 honeycomb precursor [2]. In both systems, we observe n=1 and n=2 image potential states, located 340 meV (360 meV) and 150 meV (190 meV) below the vacuum level for Ba-Ti-O (Eu-Ti-O), respectively. The states exhibit parabolic dispersions without apparent gap openings. We discuss the momentum-dependent electron lifetimes in the context of possible mini-gaps in the underlying aperiodic potential.
[1] S. Förster et al., Nature 502, 215 (2013)
[2] M. Haller et al., http://arxiv.org/abs/2510.11426
Keywords: 2PPE; time-resolved; oxide quasicrystal; 2D oxides