Momentum-dependent electron dynamics in a 2D aperiodic potential

远程有序非周期系统的电子结构和电子动力学研究尚处于起步阶段。与二维和三维周期晶体的电子动力学研究形成鲜明对比的是，准晶体的非周期势中缺乏平移对称性与传统的能带结构和离域布洛赫态的图像是不相容的。在此背景下，我们的台湾-德国项目聚焦于十二角体氧化物准晶体表面像势态的电子。它结合了二维准晶体生长和时间和动量分辨双光子光电子能谱的进步。对于生长在金属衬底上的BaTiO3和SrTiO3薄膜衍生的十二角体氧化物准晶体，可以理想地获得像势态。对于这个教科书式的电子系统，我们将研究非周期二维结构对电子能量动量色散及其飞秒动力学的影响。不同基本长度和强度的非周期电位的结果允许对诱导修饰进行系统比较。

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.