Active microwave nanodevices based on nonlocal spin injection

Emory University, Atlanta GA

Investigators

Abstract

As the scientific and engineering communities search for new information technologies capable of overcoming the current limitations of electronics in power, speed, and integration, devices exploiting both the electron's charge and spin degrees of freedom are being explored. The proposed research will investigate a new type of devices termed nonlocal spin valves, where the charge and spin flows are efficiently separated. The proposed device structure radically optimizes the operational characteristics, enabling efficient generation of microwave signals for information transmission and processing, while minimizing the negative effects of electrical current. The proposed research will explore the relationship between geometry and operational characteristics, and the possibility to incorporate these devices into nanoscale circuits that integrate signal generation, transmission, and manipulation. Several undergraduate and graduate students will be trained in the modern methods of fabrication and characterization of novel nanodevices using advanced techniques as well as gaining knowledge in fundamental and practical concepts of spintronics and materials science. Special emphasis will be placed on the outreach to the general public, through the Elementary School Science Day, annual Atlanta Science Festival, and Physics/Astronomy Open House, and by providing research experience for high school students. Development of spin-based electronics (spintronics) is motivated by the potential of reduced energy dissipation in devices that do not require charge flows, but in practice spintronic devices usually utilize large electrical currents that result in significant dissipation and even damage to devices. This research project will explore and develop nanoscale magnetic microwave oscillators driven by pure spin current produced by nonlocal spin injection in a magnetic heterostructure. Optimization of the structure will enable device operation at modest driving currents, while minimizing Joule heating and the effects of Oersted field on the spectral characteristics. The separation of the charge and the spin flows in the proposed device provides an unprecedented flexibility of the geometry, which will be exploited to optimize the spectral characteristics and efficiency, incorporate devices into nanoscale spin wave (magnonic) circuits, and achieve synchronized operation of multiple devices. The goal will be augmented by additional focus on the fundamental properties of the dynamical magnetization states at nanoscale, to address the mechanisms that enable auto-oscillation of nanomagnetic systems driven by spin currents.