Collaborative Research: Spin-Torque Devices for Microwave Nano-Electronics Based on One-Dimensional Array of Magnetic Nano-Contacts

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Collaborative Research: Spin-Torque Devices for Microwave Nano-Electronics Based on One-Dimensional Array of Magnetic Nano-ContactsThe goal of this collaborative proposal is to create an experimental prototype and develop theory of operation of a new microwave device for nano-electronics: tunable microwave oscillator based on a phase-locked array of magnetic nano-contacts coupled by a magnetic waveguide. The proposed device will employ the spin-torque effect in magnetic nano-contacts connected to a ferromagnetic spin wave waveguide. The device operational principles are based on the interactions between spin waves excited in a spin wave waveguide by spin-polarized direct current. The frequency of operation of these devices will be tunable by the external magnetic field, as well as by the direct bias current, in the frequency range between 10 and 25 GHz. The proposed novel quasi-one-dimensional device geometry based on the spin wave waveguides will also allow us to dramatically increase the coupling between the individual nano-contacts (in comparison to the usual two-dimensional geometry), and, therefore, to increase the frequency band of phase-locking and relax the restrictions on the size uniformity of the nano-contacts. This one-dimensional geometry will also increase the power output and reduce the generation linewidth of the oscillator array. The new geometry will allow us to obtain new experimental information on the mechanisms of coupling between individual spin-torque oscillators leading to their phase-locking. Intellectual merit: The proposed research program will result in the development of a new class of tunable nano-sized microwave oscillators with a unique combination of properties required for future microwave nano-electronics: compatibility with silicon-based semiconductor electronics, scalability down to the ultimate nano-scale limits, extremely low power consumption, and radiation hardness due to the absence of semiconductor elements. The proposed research will also advance our understanding of the physics of interaction between spin-polarized current and dynamic magnetization in magnetic nanostructures. Our aim is to use the full benefit of synergistic interaction between the experimental group of the University of California, Irvine, California and the theoretical group of the Oakland University, Rochester, Michigan, to achieve a breakthrough in the development of practical nano-scale device technology for microwave nano-electronics. Broader impacts: The proposed research program will impact our society in multiple ways. The new types of active nano-scale microwave devices to be developed in this program are important for the continuing leadership of the USA in electronics and magnetic recording technology. A number of graduate and postdoctoral students will be exposed to the methods of modern nano-science and nano-technology through the participation in the proposed research. The proposed program will help develop writing, presentation, and mentoring skills of our students through the participation in the manuscript preparation and conference presentations. The program will also substantially enhance and broaden students' educational experience through the collaborative research with the leading foreign and domestic research groups. The practical training in nano-fabrication offered by this program will prepare valuable specialists for the US electronics and magnetic recording industries that are currently undergoing a rapid transition from micro- to nano-scale. The program will also result in incorporating theoretical and experimental methods of nano-technology into graduate and undergraduate university curricula.