Self-similar bandgap structure and spin-polarized transport in quasiperiodic cascade junctions of ferromagnet and semiconductor

Abstract

We theoretically investigate spin-dependent transport in quasiperiodic cascade junctions of a ferromagnetic metal (FM) and semiconductor (SC), where FM and SC are arranged in the Fibonacci sequence. It is shown that spin-up and spin-down electrons possess different bandgap structures against the Rashba spin-orbit wave vector. The spin-dependent bandgap structure has the hierarchical characteristic and present self-similarity. Due to the quasiperiodicity, multiple resonant transmissions for spin-up or spin-down electrons can be observed within the bandgap; thereafter, spin polarization has multiple reversals. And it is also found that the electrical conductance can come from one kind of spin electrons around the resonant wave vector. These investigations may provide a unique way to design the devices such as spin filters and spin switches.