Spin-Orbit Currents, Spin-Transfer Torque and Anomalous Tunneling in III–V Heterostructures Probed by Advanced 30- and 40-Bands ${k}\cdot{p}$ Tunneling Methods

On the basis of tunneling magnetoresistance (TMR) spin-transfer torque (STT) experiments in (Ga,Mn)As/GaAs/(Ga,Mn)As submicronic magnetic tunnel junctions, we have analyzed the anatomy of the spin-current profiles within the heterostructures, location of strong spin-orbit interactions. Beyond the TMR, our robust 30- and 40-band k · p numerical methods reveal the strong peculiarity of the spin-currents in the antiparallel state with the evidence of a tunneling anomalous Hall effect. Using the boundary conditions corresponding to heavy-hole (HH)-to-light-hole (LH) mixing of the relevant C
_2v
symmetry at III-V interfaces of the junctions, we demonstrate that the efficiency of the transverse spin-current necessary to STT is surprisingly enhanced by the HH-to-LH mixing taking benefit of the lighter mass of the LH state.