Symmetry of spin transport in two-terminal waveguides with a spin-orbital interaction and magnetic field modulations

We analyze symmetries of spin transport in two-terminal quantum waveguide structures with Rashba spin-orbit coupling and magnetic field modulations. Constraints, imposed by the device structure, on the spin polarization of the transmitted electron beam from the waveguide devices are derived. The results are expected to provide accuracy tests for experimental measurements and numerical calculations, as well as guidelines for spin-based device designs.