Filtering spin with tunnel-coupled electron wave guides

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  • 23 August 2001
Abstract
Spintronics is an emerging field of semiconductor electronics where the electron's spin is exploited as well as its charge. Operation of spintronic devices requires the ability to create spin-polarized charge carriers in nonmagnetic semiconductors. Using Zeeman splitting of spin states in a magnetic field turns out to be impractical for spin filtering in real applications. More promising approaches employ hybrid structures with metallic or semiconducting magnetic contacts. However, fabrication of these structures poses material-science challenges and may require rather complicated chip design. Achieving spin filtering by means of intrinsic spin-dependent effects in semiconductors is therefore highly desirable. Here we propose a spin-filtering device based on the interplay of the Rashba effect and momentum-resolved tunneling between parallel electron wave guides. Spin-polarized currents are created by applying voltages or small magnetic fields. Switching between opposite spin polarizations is easily achieved. Verification of spin filtering in the device is possible via measurement of the differential tunneling conductance, which would yield the first direct observation of the Rashba effect.

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