Mach-Zehnder interferometric device for spin filtering in a GaAs/AlGaAs electron gas

Abstract

A spin filtering device using quantum spin interference is theoretically proposed in a GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit couplings. The device achieves polarized electron currents by separating spin up and spin down components without a magnetic field gradient. We find two broad spin filtering regimes, one where the interferometer has symmetrical arms, where a small magnetic flux is needed to achieve spin separation, and the other with asymmetric arms where the change in path length renders an extra phase emulating the effects of a magnetic field. We identify operating points for the device where optimal electron polarization is achieved within value ranges found in a 2D electron gas. Both device setups apply for arbitrary incoming electron polarization and operate at broad energy ranges within the incoming electron band. 03.65.Vf

Spin polarization of entangled and mixed electron states in a beam splitter geometry coupled to an electron reservoir

“…Interferometric proposals for spin polarization, such as those considered above, depend on phase coherence, so their performance will be compromised if one considers finite temperatures and connections with a reservoir 19 . Size reduction of device filters, so that they are within a phase coherence length makes operation only possible at temperatures in the mK range for systems of micrometers in length.…”