University Paris Saclay, France
Title: Transport at spin-orbit and exchange-split interfaces : giant universal asymmetry
Biography: Drouhin Henri-Jean
We report on theoretical investigations and k.p calculations of carrier tunneling in model systems and heterostructures composed of exchange-split III-V semiconductors, involving spin-orbit interaction. The media are possibly separated by thin tunnel barriers. In a 2x2 exchange-split band model, we prove that, when spin-orbit interaction is included in the conduction band of two exchange-split semiconductors, the electrons can be differently transmitted with respect to an axis orthogonal to both the axis normal to the interface and the magnetization direction. The transmission asymmetry between +k// and -k// incidence is shown to reach100% at some points of the Brillouin zone corresponding to a totally quenched transmission for given incidence angles. We establish the universal character of the transmission asymmetry, independent on the spin-orbit strength and material parameters. Particular asymmetry features are reproduced by more complete 14x14 bands calculations involving interband coupling. On the other hand, calculations performed in the valence-band of model heterostructures and including tunnel barriers in both 6x6 (without inversion asymmetry) and 14x14 k.p band models more astonishingly highlight the same trends in the transmission asymmetry which is shown to be related to the difference of orbital chirality and to the related branching of the corresponding evanescent states responsible for tunneling current. In both cases (electrons and holes), the asymmetry appears to be robust and persists even when only a single electrode is magnetic. This paves the way to new functionnalties with spinorbitronics devices.