Spin transmission control in helical magnetic fields

Abstract

We calculate spin transport in two-dimensional waveguides in the presence of
spatially modulated Zeeman-split energy bands. We show that in a regime where
the spin evolution is predominantly adiabatic the spin backscattering rate can
be tuned via diabatic Landau-Zener transitions between the spin-split bands [C.
Betthausen et. al., Science 337, 324 (2012)]. This mechanism is tolerant
against spin-independent scattering processes. Completely spin-polarized
systems show full spin backscattering, and thus current switching. In partially
spin-polarized systems a spatial sequence of Landau-Zener transition points
enhances the resistance modulation via reoccupation of backscattered
spin-polarized transport modes. We discuss a possible application as a spin
transistor.