Ferroelectric control of the electronic properties of ultra-thin metallic films

本项目的目标是利用铁电衬底的局部电场对薄膜的物理性质进行原位控制，目的是通过光电子能谱技术直接观察系统的响应。我们的目的是基于两个战略。我们将重点介绍强界面耦合的代表--铂/钛酸钡、铁/钛酸钡和铋/钛酸钡等模型体系。尤其值得注意的是，对于实现对Bi表面态的Rashba分裂强度的铁电控制，Bi/BaTiO_3界面是有趣的。由于BaTiO_3晶格参数随结构相变而变化，我们将对沉积在衬底上的薄膜系统的性质进行修改。事实上，这些体系的性质与原子距离和取向高度相关，我们可以通过基片的性质来改变这些原子距离和取向。这两种方法提供了通过光电子能谱原位控制和测量电子性质的机会，或者通过使用自发电极化，类似于施加局部电场，或者通过施加可调应变，类似于在我们的系统上使用钻石砧座单元。

The goal of this project is to control in situ the physical properties of thin films using the local electric field of a ferroelectric substrate with the aim to observe directly the response of the system by photoemission spectroscopy techniques. Our purpose is based on two strategies. We will focus on model systems like Pt/BaTiO3, Fe/BaTiO3 and Bi/BaTiO3 heterosystems that are representatives of strong interface coupling. Particularly the Bi/BaTiO3 interface is interesting to achieve a ferroelectric control of Rashba splitting strength of the Bi surface states. Owing to BaTiO3 lattice parameter change with the structural phase transitions, we will modify the properties of the film systems deposited on the substrate. In fact, the properties of these systems are highly connected to atomic distances and orientation that we could modify with the substrate properties. These two approaches offer the opportunity to control and measure in situ the electronic properties by photoemission spectroscopy either by using a spontaneous electric polarization, similar to applying a local electric field, or by applying a tunable strain, similar to using a diamond anvil cell on our systems.