Philosophy & Scope

Materials for Spintronics
and Spin-resolved Transport

Prof. Kannan M. Krishnan (Principal Investigator)

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Dilute Magnetic Dielectrics: New Spintronics Materials and Devices
Funding: NSF/ECS #0501490 (5/05-4/08)

Project summary:

This research is directed at the development of a spin injection technique utilizing a new class of materials, diluted magnetic dielectrics (DMD). DMD are both ferromagnetic at room temperature and yet insulating, the latter in contrast with diluted magnetic semiconductors (DMS). This proposal will make use of our recent observation that the presence of carriers is not required for ferromagnetism in wide band gap oxides such as TiO2 or ZnO doped with transition metal ions. Spin injection will be achieved through spin filtering in a magnetic tunnel barrier. This research will explore both fundamental material and device issues of DMD materials and their practical application. Magnetic, structural, morphological and dielectric properties of DMD thin films will be optimized in application to spin filtering barriers. For this purpose, scaling laws will be found for the physical properties with the film thickness decreasing to ~2 nanometers, an estimated optimum barrier thickness. This will also provide a new insight into the mechanisms of ferromagnetism in DMD materials. The final objective of this research is to investigate both spin filtering and electrical spin injection via DMD spin filter tunnel barriers, and to demonstrate prototype device structures using these effects. The demonstration device structures will be grown epitaxially using sputtering techniques and investigated by a variety of advanced characterization, and measurement methods. Broadly, this research will add momentum to the development of the field of semiconductor spin electronics by providing a realistic route for the development of practically useful devices. Effective injection of magnetically polarized current carriers into semiconductor structures, especially at room temperatures, and the demonstration of a practical device are the goals.

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