Electrical control of nanoscale magnetic devices.

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Nanomagnetism is one of the most active areas in science that presents us with a wide range of fundamental scientific problems as well as important and emerging technologies. Many spin-based devices are still in their infancy and a thorough understanding of the underlying materials and electronic properties and their effect on device performance will be essential for all future applications. The proposed research studies the relatively unexplored and emerging field of electric field control of metallic magnetic systems and exploits these effects in novel spin-based devices. The proposal will address the electric-field control of the intrinsic magnetic properties of transition metals and their alloys and compounds. The materials parameters to be studied include the magnetic moment density, magnetic anisotropy, Curie temperature and non-adiabatic spin-transfer parameter in magnetic transition-metal systems. All systems studied will be chosen such that they magnetically order near or above room temperature. Because these materials are conducting, the electric field (and its affect on magnetism) is confined to the near surface region; therefore this research will focus on thin films and heterostructured devices where the surfaces can dramatically affect the magnetic properties. The intellectual merit of the proposal stems from the prospect of achieving a fundamental and predictive understanding of the electric-field modification of itinerant magnetism at the nanoscale. By combining skills in thin film synthesis and device fabrication, transport and magneto-optical measurements in device structures, and advanced characterization techniques, a complete data set will be obtained. These results will test current models of magneto-electric coupling in metallic systems and it is anticipated that interesting and unexpected new magnetic phenomena will emerge in this study. The broader impact of the research will be both technical and educational. This research will address fundamental issues of magnetism and spin transport at the nanoscale and train undergraduate and graduate students in important areas of materials synthesis and characterization, device fabrication, nano-science, and nano-technology. An understanding of electric field effects on magnetism will have broad ranging impact from understanding the performance of current magnetic tunneling devices, to assessing the potential of electrical control in future spin-based electronics. The transformative goal is to provide the scientific underpinnings of next generation energy efficient, ultrafast, and ultrasmall magneto-electronic devices.