Spin and orbital blockade in quantum transport through double quantum dots

Spin and orbital degrees of freedom play different roles in quantum transport through nanostructures. In this paper, we study spin and orbital blockade in quantum transport through an asymmetric double quantum dot with inhomogeneous Zeeman splittings in the presence of crossed dc and ac magnetic fields. The interplay among electron spin resonance, Pauli exclusion, resonant tunneling, and quantum interference leads to quite different current responses for forward/backward bias in the slow/fast spin-flip regime. In particular, as change of the dc magnetic field, we observe both spin blockade (due to multiple particle spin correlation) and orbital blockade (due to quantum destructive interference) in the same system. Under suitable conditions, our system can act as bipolar spin filter, sensitive spin switch, and spin inverter.