GOALI: Spin-Transfer in Magnetic Nanostructures

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Non-Technical Abstract:This project brings together leading researchers from New York University and IBM with the aim of furthering the understanding and application of nanometer scale magnetic devices and materials. Magnetic nanostructures are widely used in technology with the most advanced applications found in information processing. Because of ever-increasing worldwide demands for data processing and storage, they form the backbone of a huge industry in the United States. Innovative research in this area at U.S industrial and university laboratories has maintained our world leadership in this vital area. It has been discovered that in miniature magnetic devices a direct electrical current can switch the direction of magnetization by a mechanism known as spin-transfer. This is an exciting development that may enable dramatic improvements in magnetic information processing and storage. There are important and fundamental questions about the nature of the interaction between the current and magnetization that this project will address through studies of magnetic nanostructures excited by spin-currents using unique high frequency measurement techniques available at NYU and magnetic imaging methods available at U.S. National Labs. This research will be integrated with the training of young scientists in this forefront area of magnetism research. Graduate and undergraduate students involved in this collaboration will gain experience by interactions between academia and industry and through exchanges between NYU and IBM. Their education will be enriched through exposure to a variety of perspectives, expertise and techniques present in an industrial setting. High school students will also participate in this research.Technical Abstract:This NSF-GOALI project brings together leading researchers in nanomagnetism from New York University and IBM with the aim of furthering the understanding of the physics of spin-transfer. Spin-transfer is a mechanism by which a spin-polarized current can reverse the magnetic orientation of a nanomagnet and induce magnetic excitations such as spin-waves. Understanding the nature of spin-transfer induced spin excitations is a very active area of present day research. The proposed research seeks to advance the understanding and application of two types of collective spin excitations that are generated by the spin-transfer interaction: magnetic solitons, which are localized spin excitations excited in nanometer scale electric contacts to magnetic thin films, and superspin currents excited in easy-plane magnetic layers. Fundamental questions regarding the lifetime, dynamics and degree of coherence of magnetic solitons will be addressed experimentally in samples in which soliton dynamics can be controlled with external perturbations (e.g. applied fields and currents). Scanning transmission x-ray microscopy will be used to image the magnetization dynamics to provide direct information on the nature of the current-induced spin excitations. Parallel theoretical work will explore the effects of temperature and other perturbations, as well as the effects of confined geometries, on soliton lifetimes and dynamics, and will explore transitions between nontopological and topological states. Superspin currents will be explored in samples consisting of proximal nanocontacts for the injection and detection of spin-currents. These experiments will aim to demonstrate and evaluate the efficiently of this newly proposed mechanism of spin transport. Graduate and undergraduate students involved in this collaboration will gain experience by interactions between academia and industry and through student exchanges between NYU and IBM. Their education will be enriched through this integrated experimental and theoretical project, as well as the variety of perspectives, expertise and techniques present in an industrial setting. High school students will also be encouraged to participate in this research project.