Spin-dependent tunneling properties of Thue-Morse sequence in ferromagnet/semiconductor/ferromagnet cascade junctions

We investigate the spin-dependent transport in aperiodic cascade junctions of semiconductors, where semiconductors are arranged in the Thue-Morse sequence. We have calculated the spin-dependent transmission and the spin polarization with a transfer matrix method in these cascade junctions. It is shown that a spin-dependent bandgap structure appears by changing the generation and the Rashba spin-orbit wave vector. As a result, around resonant wave vectors, high spin polarization has been observed and the spin polarization has been reversed, and the spin conductance exists the value of zero by tuning the Rashba spin-orbit coupling. Our investigations may provide a way to design spin filters and spin switches.