Spin-Dependent Quasiparticle Transport in Aluminum Single Electron Transistors

We investigate the effect of Zeeman-splitting on quasiparticle transport in normal-superconducting-normal (NSN) aluminum single electron transistors (SETs). In the above-gap transport the interplay of Coulomb blockade and Zeeman-splitting leads to spin-dependence of the sequential tunneling. This creates regimes where either one or both spin species can tunnel onto or off the island. At lower biases, spin-dependence of the single quasiparticle state is studied and operation of the device as a bipolar spin filter is suggested.