Towards pure spin currents in epitaxial all oxide heterostructures

在过去的几年里，已经成功地实现了纯自旋电流的产生和检测，即角动量的流动，没有任何伴随的电荷电流。这为基础物理实验和自旋电子学的新应用开辟了迷人的机会。然而，对与纯自旋电流相关的现象和适合于它们研究的材料系统的深刻理解仍然缺乏。本研究计划的主要目的是系统地研究所有氧化物异质结构中的纯自旋电流物理，这是有希望的，但迄今为止很少研究。一方面，计划中的实验有望对氧化物材料中与自旋轨道相互作用相关的丰富多样的现象及其对特定材料参数的依赖提供深刻的理解。另一方面，该项目旨在开发和研究具有大自旋霍尔角的新型材料，即具有较高的发电效率和纯自旋电流检测效率。此外，本文还通过应变、氧空位和温度对氧化物中自旋轨道耦合的可调性进行了研究。提高自旋电流产生和检测效率是纯自旋电流在高效自旋电子器件中应用的先决条件。通过激光分子束外延制造高质量的氧化物异质结构，系统地研究基于纵向自旋塞贝克效应和自旋霍尔磁阻的纯自旋电流产生和检测实验，将实现雄心勃勃的项目目标。申请人在薄膜技术和自旋电流现象的实验表征技术方面贡献了广泛的专业知识，以成功实施雄心勃勃的研究计划。

Over the last years, the generation and detection of pure spin currents, i.e. the flow of angular momentum without any accompanying charge current, has been successfully realized. This opened fascinating opportunities for fundamental physics experiments and novel applications in spin electronics. However, a profound understanding of the phenomena associated with pure spin currents and the materials systems suitable for their study is still missing. The main objective of this research proposal is the systematic study of pure spin current physics in all oxide heterostructures, which are promising for this purpose but hardly investigated so far. On the one hand, the planned experiments are expected to provide a profound understanding of the rich variety of phenomena associated with spin-orbit interaction in oxide materials and its dependence on the specific material parameters. On the other hand, the project aims to develop and investigate novel materials with large spin Hall angle, i.e. with a large efficiency for electrical generation and detection of pure spin currents. Moreover, it aims at the tunability of spin-orbit coupling in oxides via strain, oxygen vacancies, and temperature. The boost of the efficiency for spin current generation and detection is a prerequisite for the application of pure spin currents in efficient spintronic devices. The ambitious project objectives will be met by fabricating high-quality oxide heterostructures by laser-molecular beam epitaxy and by systematically studying pure spin current generation and detection in experiments based on longitudinal spin Seebeck effect and spin Hall magnetoresistance. The applicants contribute broad expertise in both thin film technology and the experimental characterization techniques for spin current phenomena to the successful implementation of the ambitious research program.