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Graduation Commencement

Condensed Matter Seminar Abstract

Date: Oct 18    (217A Conference Room Shap Lab at 2:00pm)

Speaker: Jean J. Heremans, Ohio University

Title: Spin-dependent mesoscopic charge transport in narrow-gap heterostructures

Abstract:

The narrow-gap semiconductors InSb and InAs provide a rich platform for spin physics and spin-dependent transport, as they combine substantial spin-orbit interaction with lithographically accessible mean-free-paths and spin coherence lengths. We present mesoscopic experiments involving ballistic spin-dependent transport under spin-orbit interaction, in structures fabricated on the heterostructures InSb/InAlSb and InAs/AlGaSb. We demonstrate spin-dependent reflection off a lithographic barrier, whereby a spin-unpolarized injected beam yields two spin-polarized side beams and one unpolarized specular beam. We further show transverse magnetic focusing experiments, wherein we can study the contribution of individual spin-split Fermi contours, of interest to obtain spin separation by cyclotron motion. Finally, antidot lattices and loop arrays exhibit Altshuler-Aronov-Spivak quantum interference oscillations, from which spin-orbit scattering lengths and phase coherence lengths can be deduced. These examples point to the promising utilization of the spin degree of freedom in nanoscale electronics.