Long-Range Spin Transport in Light-Metal Alloys

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Non-Technical AbstractMagnetic materials are ubiquitous in technology, from the permanent magnets all around us to the precisely engineered magnetic materials in the powerful hard disk drives that enable cloud data storage. Spintronics is the scientific field that underpins such technologies, based on control of the property of electrons known as spin. One major limitation in the field of spintronics is that is very challenging to move electron spins over even microscopic distances; the ability to do so would unlock extraordinary technological potential, including massively reducing the power consumption of computers. This project is addressing exactly this challenge, not only seeking long-range transport of electron spins, but doing so in industrially-relevant materials based on simple metals. In addition to advancing the fundamental understanding of the physics of this process, broader impacts are being achieved through the high technological relevance of the work, through education and training of graduate and undergraduate students (thus contributing to a skilled US workforce in the electronic device sector), and through outreach to the public in conjunction with the Science Museum of Minnesota. Technical Abstract In spintronics, injection of spins across interfaces, and their subsequent transport, is central to the function of many devices. Such devices have already massively impacted data storage and processing, with potential for further advances. One particularly exciting prospect is long-range spin transport through materials, which could realize transformative capabilities such as spin interconnects and spin accumulation sensors. Fundamental research on long-range spin transport has focused almost entirely on semiconductors and insulators, despite metallic spintronics being well-established and amenable to technology. This is because spin diffusion lengths in conventional polycrystalline non-magnetic metallic thin films are typically only 100’s of nm, limited by defect-induced spin relaxation. This project seeks to directly alleviate this limitation. Orders-of-magnitude increases in spin diffusion lengths in nonmagnetic metallic thin films are being sought via novel application of rationally-designed light-metal alloys, using theory-guided compositional tuning of electronic structure and band filling to controllably suppress spin relaxation. In addition to advancing the fundamental understanding of the relevant physics, broader impacts are being achieved through the high technological relevance of the work, through education and training of graduate and undergraduate students, and through outreach to the public in conjunction with the Science Museum of Minnesota.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.