The Effect of Anisotropy on Resonant Tunnelling Spin Polarization in Type-II Heterostructures

Abstract

The effect of anisotropy on resonant tunnelling spin polarization in type-II semiconductor heterostructures is investigated within the envelope function approximation. Calculations are performed using an 8 Â 8 k Á p matrix Hamiltonian which includes the interband coupling between electrons and holes as well as the non-parabolicity and anisotropy of the energy band structure. The polarization is due to constant applied magnetic field directed along the growth directions of samples which are grown at arbitrary angles with respect to the c½001 axes. Using spin-dependent boundary conditions and the transfer matrix method, an analytical expression for the spin polarization is obtained. Numerical calculations of the polarization reveal that it is highly sensitive to the anisotropy parameters of the model. Even under relatively weak magnetic fields polarizations of up to 75% are predicted.

Numerical solution of multiband <b>k.p</b> model for tunnelling in type-II heterostructures

“…In this article, the main aim was to communicate the very general method that was developed in Sections 2.1-2.4. Since this method was based on the well-established multiband k·p model, it will be useful for theoretical studies of a wide variety of other interesting phenomena which occur in semiconductor heterostructures, for example, anisotropy (band warping) 26 and spin-splitting (bulk, structural and due to an applied magnetic field). …”

Electron-spin polarization in symmetric type-II quantum wells from bulk inversion asymmetry

“…[38][39][40] We make use of well-established boundary conditions that satisfy two fundamental physical requirements: ͑1͒ continuity of the envelope wavefunctions at the interface and ͑2͒ continuity of the probability currents at the interface. 41 At zϭ0, the first of these two requirements can be expressed mathematically as…”