Blocked electron transmission/reflection by coupled Rashba–Zeeman effects for forward and backward spin filtering

We present a theory for studying the quantum dynamics of both the transmission and reflection behavior of a two-dimensional electron gas across a planar potential step within a quantum well. In our model, we introduce the combined effect of the Rashba–Zeeman coupling on the conduction electrons. Our results demonstrate that as the energy of an incident or a transmitted electron stays within the Zeeman energy gap, both Klein reflection and Klein tunneling occur in this Rashba–Zeeman coupled electronic system, where the former corresponds to a backward spin filter while the latter to a forward spin filter. Meanwhile, our system also predicts a critical incident angle beyond which the electron tunneling will be fully suppressed. Such distinctive spin-filtering features are expected to give rise to a variety of applications in both spintronics and quantum-computation devices.