Variational Rashba Effect in GaAlAs/GaAs Heterojunctions

The Rashba alpha parameter at the Fermi energy of 2DEGs in AlGaAs/GaAs heterojunctions is calculated with a new variational solution to the multi-band envelope-function effective Schroedinger equation based on the 8-band kp Kane model for the bulk. Modified Fang-Howard trial wave-functions that depend on spin and satisfy spin-dependent boundary conditions, are introduced; and the spin splitting is obtained by minimizing the total energy of the 2DEG. The results are compared with simpler model calculations and shown, in particular, to be quite sensitive to the barrier penetration of the first subband wave-function in these heterojunctions.