Scalable Digital Spin Logic Devices

University Of Maryland, College Park, College Park MD

Investigators

Abstract

This project will combine expertise of PI in spin transport and of Co-PI in multiferroic materials & devices to develop a new logic paradigm capable of circumventing the fundamental limitations of charged-based circuits. The team will exploit the interactions between electron spin and solid-state magnetism in a scalable architecture which avoids the shortcomings relevant to electronic logic circuit operation. Non-equilibrium spin (injected into a nonmagnetic, spin-conserving channel material from single-domain ferromagnetic bits) can couple to other magnetic bits through spin torque and exchange force. The actuation of magnetization switching and therefore logic processing, is enabled by effective fields induced by interfacial magnetostrictive strain from multiferroic and piezoelectric material heterostructures in a virtually dissipation-free way. These concepts of materials, coupling, and actuation are natural themes which guide the research tasks and will lead toward realization of a technology capable of satisfying the five fundamental requirements for viable computing systems: non-linearity, gain, concatenability, feedback elimination, and a complete set of Boolean operations. The Intellectual Merit of the proposed research is that it directly addresses the fundamental scientific challenges that must be overcome to realize an all-spin logic device technology. Silicon and germanium will be studied as model semiconductor spin-conserving channel materials. The spin torque and exchange coupling strengths at the interface between ferromagnet and channel material will be measured. Piezoelectric voltage-mediated control over magnetic switching barriers will be achieved, and switching of a magnetic bit using non-equilibrium spins in a neighboring non-magnetic channel material will be demonstrated for the first time. The result will be a detailed understanding of the necessary conditions for using the effective magnetic field generated by voltage-controlled magnetostriction to effect rapid magnetization switching with minimal forcing by non-equilibrium spins and minimal energy dissipation. The Broader Impact of the proposed activity is in the potential of this new logic processing paradigm to continue performance trends (established through decades of scaling) in charge-based electronic systems with significant economic, environmental, and societal ramifications. The advantages afforded by spintronics devices of enabling lower-power, instant-on electronics allow increased device portability and are especially important in light of today?s increasing energy costs and its environmental damage. Additional Broader Impact is achieved through training graduate students in diverse aspects of science and engineering including semiconductor device design, processing, measurement, and spintronics; and activities designed to broaden understanding by elementary and high-school students, parents, and the general public of the historical importance of scaling in the semiconductor electronics industry and the challenges faced as scaling reaches its end in the next decade.