钙钛矿结构铱酸锶薄膜中关联拓扑量子态的同步辐射光源角分辨光电子能谱研究

The interplay of strong spin-orbit interactions and medium electron correlation effects in 5d transition metal oxides, for example iridium oxides (iridates), emerges as an ideal platform to investigate correlated topological quantum states. Theoretical studies have predicted that perovskite SrIrO3 hosts novel topological quantum states and emerges as a key building block for engineering topological quantum phase transitions in complex oxide heterostructures, while it remains elusive from the experimental side. Thus, for further developing strongly correlated topological theory, it is of great importance to experimentally realize and manipulate the correlated topological states in SrIrO3. However, it is very challenging due to its three-dimensional electronic structures and spin textures, as well as locking of perovskite SrIrO3 single crystals. In this project, we propose to perform synchrotron-radiation based UV and soft X-ray spin- and angle-resolved photoemission spectroscopy to investigate the correlated topological states in perovskite SrIrO3 thin films and heterostructures grown in-situ by pulsed laser deposition. By performing systematical measurements on electronic structures and spin textures, and comparing with theoretical calculations, we expect to resolve the correlated topological states. Moreover, we expect to tune their properties by engineering crystalline orientation, strain, dimensionality and heterointerface. We believe our work will provide new insights on the correlated topological states in iridates and pave the way for future applications in oxide electronics and spintronics.

探索关联电子体系中新奇的拓扑量子态是目前凝聚态物理和材料科学的重要研究前沿。5d过渡金属氧化物，如钙钛矿结构铱酸锶（SrIrO3），由于存在强自旋轨道耦合和中等强度的电子关联，理论研究预测其表面和体相同时存在多种关联拓扑量子态。然而，实验上确定并调控其关联拓扑态存在很多挑战，如需要结合薄膜制备和原位的电子及自旋性质的高分辨测量，及区分材料表面和体相的拓扑态等。针对上述困难，本项目拟利用脉冲激光沉积和基于同步辐射紫外和软X射线光源的角分辨光电子能谱（ARPES）和自旋分辨ARPES原位地研究SrIrO3薄膜及异质结构表面及体相的电子结构和自旋性质。结合理论计算，有望确定是否存在表面和体相的关联拓扑量子态。进一步通过晶向、应力、维度和界面调控等手段实现对关联拓扑量子态操控，为实现新型多功能（自旋）电子学器件奠定物理基础。

探索关联电子体系中新奇的拓扑量子态是目前凝聚态物理和材料科学的重要研究前沿。4d/5d过渡金属氧化物，如钙钛矿结构了钌酸锶/铱酸锶（SrRuO3/SrIrO3），由于存在强自旋轨道耦合和中等强度的电子关联，理论研究预测其表面和体相同时存在多种关联拓扑量子态。然而，实验上确定并调控其关联拓扑态存在很多挑战，如需要结合薄膜制备和原位的电子及自旋性质的高分辨测量，及区分材料表面和体相的拓扑态等。针对上述困难，本项目利用脉冲激光沉积和ARPES原位地研究SrRuO3及SrIrO3薄膜的电子结构。结合理论计算，确定了SrRuO3中存在磁性外尔半金属量子态；利用结构调控，确定了SrIrO3中维度驱动金属绝缘体相变的微观机理；进一步通过晶向、结构和界面调控等手段实现对SrIrO3异质结构中磁各向异性的操控，为实现新型多功能（自旋）电子学器件奠定物理基础。