Spin filtering through ballistic nanojunctions, the role of geometry and of spin orbit interaction

We suggest a spin filter scheme using T-stub nanometric crossjunctions patterned in two dimensional electron gases (2DEGs) in the presence of spin orbit interaction (SOI). We compare the effects of SOI arising from vertical confinement of charge carriers in the well, Rashba or alpha-SOI, with SOI generated by lateral confinement of the wire, beta-SOI. We show that beta coupling can be more effective in generating a spin polarized current as compared to alpha-SOI. We also compare the efficiency of the T-stub filter with the one of the X shaped cross junction.