Condensed Matter and Biological Physics Seminars

Spin-dependent transport phenomena in semiconductors form part of wider endeavors in spin electronics. The narrow-gap semiconductors InSb and InAs provide a rich platform for spin-dependent transport, as they combine substantial spin-orbit interaction terms, with lithographically accessible low-temperature 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, utilizing an injector aperture directing the carriers towards a barrier, and a collector aperture detecting carriers reflected off the barrier. A spin-unpolarized injected beam yields two spin-polarized side beams and one unpolarized specular beam. We further show transverse magnetic focusing experiments, to study the contribution of individual spin-split Fermi contours in ballistic experiments, 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 synthesis of spin electronics and nanoscale electronics.