Fabrication and characterization of single and few layer graphene spin valves leading to optimization of spin relaxation length as well as spin voltage dependence on carrier concentration

Yuri J Kubo, Purdue University

Abstract

Several characteristics of graphene are studied in this thesis in order to show trends relating the material properties of graphene to the use of graphene as a channel material for All Spin Logic, an effort to use electron spin as a means of transferring and storing information. These efforts have led to two major findings. The first is a characterization of the number of layers of graphene in a spin valve for the optimization of the spin relaxation length, a parameter tied directly to the magnitude of spin voltage. The second is a description of the dependence of spin voltage on carrier concentration based on the interface between the ferromagnetic contacts and the graphene. Along with these findings, the fabrication and measurement processes are also described in great detail. From the exfoliation process to photoresist spin recipes to ground isolation during electrical characterization, all of the information needed to reproduce this work is contained within this thesis intended to be an aid for future graphene work. Using these processes, clean graphene devices were fabricated in an academic setting that had electrical characteristics superior to state of the art devices developed in other research efforts.

Degree

M.S.E.C.E.

Advisors

Appenzeller, Purdue University.

Subject Area

Electrical engineering

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