Collaborative Research: Design and Demonstration of Persistent Spin Textures in Ferroelectric Oxide Thin Films

现代电子学是基于移动电子通过由半导体（如硅）制成的纳米级晶体管。计算能力的指数级增长是通过缩小晶体管的尺寸和增加晶体管的密度实现的。由于晶体管的尺寸接近原子尺度，进一步小型化是不可能的。计算和信息处理的另一种途径是利用基本粒子的固有特性——自旋。自旋电子学将电子学与自旋相结合，使信息处理和存储设备具有更高的能源效率和更少的热量产生。磁场的限制特征仍然是在磁性材料的纳米尺度上传输自旋而不丢失存储的信息。该项目利用了相对论量子力学效应——自旋-轨道相互作用——以及晶体对称性来保护自旋在非磁性材料中传播时的状态。研究小组将实验工作与模拟相结合，以实现一种用于自旋电子学的新型薄膜氧化物材料。在整个项目中，多个层次的学生教学和培训交织在一起。该项目将通过公共宣传活动、课程开发和招募学生参与跨学科实验研究，扩大代表性不足的学生对STEM的参与。教育方面的影响延伸到高中教师，他们将被招募参与研究，并为他们的课堂开发材料物理模块。这些努力将通过赋予学生未来STEM职业所需的解决问题的技能来影响下一代劳动力。人们渴望识别超越摩尔定律的设备和技术，这促使人们越来越多地关注一系列替代计算设备，包括使用自旋而不是电子的电荷。自旋轨道电子学领域的限制特征是难以从传统的半导体和磁性材料中获得长寿命和完全可控的自旋。这个项目的目标是设计、发现和证明铁电氧化物包含一种对称保护的持久自旋结构，这使得自旋中编码的信息在传播过程中对损坏具有鲁棒性。这个项目的独特之处在于使用原子拓扑来实现具有自旋轨道相互作用的体材料中的新型自旋纹理，而不是通过传统的量子阱结构来微妙地平衡多个难以控制的相互作用。该项目将理论、模拟和综合实验与复杂的薄膜氧化物生长方法相结合，以建立新的自旋织构理论和模型，识别和合成具有对称性自旋织构的新型铁电氧化物，并探索自旋织构的电场可调性。该项目的成果包括复杂材料中自旋织构的新的描述和预测理论，新型复杂过渡金属氧化物铁电体的实现，以及基于自旋的器件的演示。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Modern electronics are based on moving electrons through nanoscale transistors made of semiconductors such as silicon. The exponential growth in computing power has been realized by shrinking the size of transistors and increasing their density. As the dimensions of transistors approach atomic scales, further miniaturization is not possible. An alternative route to computing and information processing exploits spin, an intrinsic property of elementary particles. Spintronics combines electronics with spin, allowing for devices for information processing and storage that have superior energy efficiency and reduced heat-generation. The limiting feature for the field remains transporting spins across nanoscale dimensions in magnetic materials without losing the stored information. This project exploits a relativistic quantum mechanical effect – spin-orbit interaction – along with crystalline symmetries to protect the state of the spin as it travels in non-magnetic materials. The research team will combine experimental work with simulations to realize a new class of thin film oxide materials for spintronics. Teaching and training of students at multiple levels is interwoven throughout the project. The project will broaden STEM participation by underrepresented students through public outreach events, curriculum development, and recruiting students to participate in interdisciplinary experimental research. The educational impact extends to high-school teachers, who will be recruited to participate in research and develop materials physics modules for their classrooms. These efforts will impact the next-generation workforce by endowing students with the problem solving skills needed for future careers in STEM.The desire to identify beyond Moore’s Law devices and technologies has driven increasing attention on a range of alternative computing devices, including using the spin rather than the charge of an electron. The limiting feature for the field of spin-orbit-based electronics is the difficulty in attaining both long-lived and fully controllable spins from conventional semiconductor and magnetic materials. The goal of this project is to design, discover, and demonstrate ferroelectric oxides embodying a symmetry-protected persistent spin texture, which permits information encoded in the spins to be robust to corruption as they propagate. Unique to this project is the use of atomic topology to achieve the novel spin textures in bulk materials with spin-orbit interactions, rather than by delicately balancing multiple, hard to control, interactions through conventional quantum-well structures. The project couples theory, simulation, and comprehensive experimentation with sophisticated thin film oxide growth methods to develop new theories and models for spin textures, identify and synthesize novel ferroelectric oxides exhibiting symmetry-determined spin textures, and explore electric-field tunability of the spin textures. Outcomes of the project include new descriptive and predictive theories for spin textures in complex materials, realization of novel complex transition metal oxide ferroelectrics, and demonstration of spin-based devices.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.