We explore from first-principles calculations the ferroelectric material Pb5Ge3O11 as a model for controlling the spin-orbit interaction (SOC) in crystalline solids. The SOC has a surprisingly strong effect on the structural energy landscape by deepening the ferroelectric double well. We observe that this effect comes from a specific Pb Wyckoff site that lies on the verge of a natural cavity channel of the crystal. We also find that a unique cavity state is formed by the empty 6p states of another Pb site at the edge of the cavity channel. This cavity state exhibits a sizeable spin splitting with a mixed Rashba-Weyl character and a topologically protected crossing of the related bands. We also show that the ferroelectric properties and the significant SOC effects are exceptionally robust against n-doping up to several electrons per unit cell. We trace the provenance of these original effects to the unique combination of the structural cavity channel and the chemistry of the Pb atoms with 6p orbitals localizing inside the channel.
Orbital-Energy Splitting in Anion Ordered Ruddlesden-Popper Halide Perovskites for Tunable Optoelectronic Applications
能带边缘的电子轨道特性对钙钛矿光伏材料的电学、光学和缺陷性质起着重要的决定作用。建立基础原子轨道和光电性质之间的关系作为最大化光伏性能的指导是非常期望的。在这里，使用第一性原理计算并以阴离子有序Ruddlesden-Popper（RP）相卤化物钙钛矿Cs $_{n+1}$ Ge $_n$ I $_{n+1}$ Cl $_{2n}$为例，我们演示了如何合理地优化光电性能（例如，带隙、跃迁偶极矩阵元、载流子有效质量、带宽）。结果表明，降低B位原子p轨道的分裂能$|Δc|$可以有效地降低带隙和载流子有效质量，同时大大提高可见光区的光吸收。因此，通过双轴压缩应变很好地建立了与$Δc$的轨道-性质关系。最后，它表明，这种方法可以合理地扩展到其他几个非立方卤化物钙钛矿在导带边缘具有类似的p轨道特性。因此，我们相信我们提出的轨道工程方法为理解和优化层状钙钛矿太阳能电池的器件性能提供了原子级指导。
Orbital-Selective Engineering of Strain-Tunable Chern Insulators in Momentum Space
Key Laboratory of Magnetism and Magnetic Functional Materials (Lanzhou University), Ministry of Education（磁性功能材料教育部重点实验室（兰州大学））；Henan Institute of Technology（河南工学院）；School of Physics Science and Technology, Lanzhou University（兰州大学物理科学与技术学院）
Electrically tunable orbital coupling and quantum light emission from O-band quantum dot molecules
Walter Schottky Institute, TUM School of Natural Sciences, Technical University of Munich（慕尼黑工业大学沃尔特·施特克特研究所）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）；Center for Quantum Engineering (ZQE) and School of Computation, Information and Technology, Technical University of Munich（慕尼黑工业大学量子工程中心与计算、信息与技术学院）；Julius-Maximilians-Universität Würzburg, Physikalisches Institut, Lehrstuhl für Technische Physik（维尔茨堡大学物理系技术物理教席）；Walter Schottky Institute, Technical University of Munich（慕尼黑工业大学沃尔特·施特克特研究所）；Saqura Technologies GmbH（萨库拉技术有限公司）；Karlsruhe Institute of Technology, Institute of Photonics and Quantum Electronics IQST（卡尔斯鲁厄理工学院光子学与量子电子学研究所）
