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

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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.