GOALI: Design and Fabrication of a Hybrid Drift Diffusion Spin Valve to Investigate Graphene Spin Transport Properties for Spintronics

Portland State University, Portland OR

Investigators

Abstract

Electronics are based on the manipulation of electrons and other charge carriers. In addition to charge, electrons have spin that can be manipulated with magnetic and electric fields, resulting in a spin-polarized current that carries more information than is possible with charge alone. Spin-transport electronics demonstrate advantages for design of novel devices to overcome the limitation of traditional electronics. Graphene, a single atomic layer of graphitic carbon, has unique physical properties that make it very attractive for spintronic applications. Various experimental demonstrations of spin transport in graphene have been achieved by interfacing graphene with other classes of materials, including ferromagnetic materials, semiconductors, and metal electrodes. However, the experimental results are still well below theoretically predicted values. To bridge this gap, two areas of research is proposed: fabrication of graphene and a design of a novel device to advance graphene-based spintronic devices that will be capable of higher data transfer speeds, increased processing power and memory density, and added storage capacity. The PSU and Intel partnership will significantly enhance the transfer of research results to industry. It will also broaden the training and experiences of graduate and undergraduate students involved and facilitate active interactions between PSU and Intel scientists and train them in emerging areas of materials science and device technology, where fundamental insights can result in profound and rapid practical advances. The participation of underrepresented undergraduates in this project will be leveraged through ongoing NSF funded REU and LSAMP programs, the McNair Scholarship program, and the Undergraduate Research and Mentoring Program at PSU. This proposal aims at the design and fabrication of novel hybrid diffusion drift spin valve (HDDSV) arrays through processes that are adaptable to industry. The proposed device will allow systematic investigations of graphene spin transport parameters including spin lifetime, spin diffusion length, and polarization injection efficiency by variations of device components and dimensions. The non-local spin valves (NLSV) device employed to study graphene spin transport has resulted in experimental values that are orders of magnitude lower than those theoretically predicted. The proposed HDDSVs are uniquely designed to detect nonlocal signals originating from a spin accumulation of spin polarized charge carriers, which occurs away from the influence of ferromagnetic (FM)/tunnel barrier (TB)/Graphene interfaces. This research effort represents a multi-disciplinary approach of combining graphene synthesis, device fabrication, and data measurement and analysis, to advance the understanding of graphene spin transport properties. The overall goal of this research is to address the principle roadblocks to the advancement of graphene spintronics. The novel device configuration will have the capability of isolating the effects of ferromagnetic contacts from graphene spin transport measurements, while enabling spin and charge carrier manipulation simultaneously. The proposed device will allow new spin transfer phenomena to be examined. The study of such a novel device will reveal the fundamental effects of ferromagnetic contacts and charge carrier drift in relation to spin diffusion lengths and spin lifetimes in a graphene transport channel. The academic and industrial research teams' complementary expertise and comprehensive capabilities warrant success of the proposed goals.