Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland.
Department of Quantum Matter Physics, University of Geneva , 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
Nano Lett. 2017 Apr 12;17(4):2561-2567. doi: 10.1021/acs.nanolett.7b00317. Epub 2017 Mar 16.
Engineering the electronic band structure of two-dimensional electron liquids (2DELs) confined at the surface or interface of transition metal oxides is key to unlocking their full potential. Here we describe a new approach to tailoring the electronic structure of an oxide surface 2DEL demonstrating the lateral modulation of electronic states with atomic scale precision on an unprecedented length scale comparable to the Fermi wavelength. To this end, we use pulsed laser deposition to grow anatase TiO films terminated by a (1 × 4) in-plane surface reconstruction. Employing photostimulated chemical surface doping we induce 2DELs with tunable carrier densities that are confined within a few TiO layers below the surface. Subsequent in situ angle-resolved photoemission experiments demonstrate that the (1 × 4) surface reconstruction provides a periodic lateral perturbation of the electron liquid. This causes strong backfolding of the electronic bands, opening of unidirectional gaps and a saddle point singularity in the density of states near the chemical potential.
工程二维电子液体（2DEL）的电子能带结构，这些 2DEL 被限制在过渡金属氧化物的表面或界面处，这是释放它们全部潜力的关键。在这里，我们描述了一种新的方法来调整氧化物表面 2DEL 的电子结构，证明了在前所未有的长度尺度上（与费米波长相当）以原子级精度对电子态进行横向调制。为此，我们使用脉冲激光沉积在具有（1×4）面内表面重构的锐钛矿 TiO 薄膜上进行生长。通过光刺激化学表面掺杂，我们诱导出具有可调载流子密度的 2DEL，这些 2DEL 被限制在表面以下几个 TiO 层内。随后的原位角分辨光发射实验表明，（1×4）表面重构提供了电子液体的周期性横向微扰。这导致能带强烈的反向折叠，在化学势附近的态密度中打开单向间隙和鞍点奇点。
