Tailoring interface functionality of complex oxide heterostructures - A neutron and x-ray study

非技术摘要：复杂的过渡金属氧化物异质结构代表了一个新兴的和快速增长的领域，具有显着的科学价值和潜在的应用在自旋电子学，催化剂，太阳能电池等。大量的新的物理现象可以出现在氧化物异质结构中的不同材料的界面处，这是无法实现的散装成分。本项目通过调整衬底的几何形状和表面取向来创建和操纵新型界面功能，从而研究过渡金属氧化物异质结构中的这种新现象。重要的是，该项目作为培训下一代中子和同步加速器X射线散射科学家的平台，有助于促进国家实验室尖端设施的用户社区。除了培训研究生和本科生外，该项目还支持高中教师和K-12学生参与的科学研究活动，以及为密歇根州社区学院的学生开发和举办研讨会的活动。技术摘要：该项目通过创造和操纵新的界面功能来研究相关过渡金属氧化物异质结构中的涌现量子现象。调整基板的几何形状和表面取向引起不同的极性表面终端，键连接，和八面体的扭曲，预计影响电子和轨道重建以及磁和结构耦合的接口。因此，这可以极大地改变顶部生长的氧化物异质结构的物理特性，为新的物理和材料研究提供了一条途径。该项目采用了两种独特和互补的技术，即，极化中子反射测量法和极化x射线吸收光谱法，提供了过渡金属元素的高深度分辨率和特征指纹，以决定性地确定界面磁性和电子状态的性质。

Non-technical Abstract: Complex transition-metal oxide heterostructures represent an emerging and rapidly growing field with both significant scientific merits and potential applications in spintronics, catalysts, solar cells, etc. A plethora of novel physical phenomena can arise at the interface of dissimilar materials in oxide heterostructures that are not attainable in the bulk constituents. This project investigates such novel phenomena in transition-metal oxide heterostructures via creation and manipulation of novel interface functionalities by tuning the substrate geometry and surface orientation. Importantly, this project serves as a platform to train the next-generation neutron and synchrotron x-ray scattering scientists, helping to promote the user community of the cutting-edge facilities in national laboratories. In addition to training graduate and undergraduate students, this project also supports the scientific research activities engaging high school teachers and K-12 students, as well as the activities of developing and presenting workshops to students in community colleges in Michigan. Technical Abstract: The project investigates the emergent quantum phenomena in correlated transition-metal oxide heterostructures via creation and manipulation of novel interface functionalities. Tuning the substrate geometry and surface orientation gives rise to diverse polar surface terminations, bond connections, and octahedral distortions, which are anticipated to affect electronic and orbital reconstruction as well as magnetic and structural coupling at the interfaces. Consequently, this can drastically alter physical properties of oxide heterostructures grown atop, providing a pathway to new physics and materials research. This project utilizes two unique and complementary techniques, i.e., polarized neutron reflectometry and polarized x-ray absorption spectroscopy, which offer high depth resolution and characteristic fingerprint of transition-metal elements to decisively determine the nature of interfacial magnetic and electronic states.