Multichannel field-effect spin barrier selector

The advent of spintronics has resulted in the study and design of spin manipulated devices used as information processors, quantum computing elements, spinpolarized diodes, spin-valve read heads, and electrooptical modulators, to name just a few. The spin-orbit (SO) interaction, due to spatial asymmetry in zincblende lattices or sample design, doping profile or applied gate voltages, plays a fundamental role on these systems, especially on spin-dependent tunnelling. The SO interaction couples the electronic momentum to the spin degrees of freedom, and lifts the spin degeneracy for structures fabricated in zincblende materials. The narrower the energy gap of the host material, the stronger these effects will appear on the transport and optical properties. We present here a detailed analysis of the complexity of bulk electronic structure, derived from kinetic energy plus the full SO Hamiltonian including Bychkov-Rashba and all three Dresselhaus contributions. Then, we study SO effects on spin-polarized current in double-barrier resonant (DBR) devices, and analyze how the anisotropy on the spin orientation and polarization of spinor states can be used to select and optimize channels for vertical transport in the system. Recent publications have proposed the manipulation of linear Rashba and Dresselhaus terms in the SO interaction. The cancellation of linear terms leads to drift-diffusive lateral transistors, in contrast to the ballistic operation of the Datta-Das device. Perel et al have also reported on the evolution of the spin orientation with 2D transverse momentum, and explored the tunnelling through a single barrier with different III-V materials, driven only by the linear k‖ Dresselhaus term. A time-dependent spin manipulation scheme has been recently proposed. Let σ = + (−) label the spin-up (spin-down) state. The carrier dynamics, driven by the kinetic energy plus full SO Hamiltonian, is dictated by [ H ++ H +− H −+ H −− ] [ F+(z) F−(z) ] e‖ = E [ F+(z) F−(z) ] e‖.