Spin-orbit assisted chiral-tunneling at semiconductor tunnel junctions: Study with advanced 30-band k • p methods

In this paper, we report on theoretical investigations and advanced k • p calculations of carrier forward scattering asymmetry (or transmission asymmetry in tunnel junction) vs. their incidence through magnetic tunnel junctions (MTJ) made of semiconductors involving spin-orbit interactions (SOI). This study represents an extension to our previous contribution¹ dealing with the role, on the electronic forward and backward transmission-reflection asymmetry, of the Dresselhaus interaction in the conduction band (CB) of MTJs with antiparallel magnetized electrodes. The role of the atomic-SOI in the p-type valence band (VB) of semiconductors is investigated in a second step. We first developed a perturbative scattering method based on Green's function formalism and applied to both the orbitally non-degenerated CB and degenerated VB to explain the calculated asymmetry in terms of orbital-moment tunneling branching and chirality arguments. This particular asymmetry features are perfectly reproduced by advanced k • p tunneling approaches (30-band) in rather close agreement with the Green's function methods at the first perturbation order in the SOI strength parameter. This forward scattering asymmetry leads to skew-tunneling effects involving the branching of evanescent states within the barrier. Recent experiments involving non-linear resistance variations vs. the transverse magnetization direction or current direction in the in-plane current geometry may be invoked by the phenomenon we discuss.