Spin-orbit Coupling Effects On Electron Transport In Ferromagnet / Rashba Quantum Well / Ferromagnet Heterostructure Impact

Using the transfer matrix method, the coherent quantum transport, which is in GaAs/GaAlAs semiconductor multi-quantum wells (SMW) with ferromagnetic(F) electrodes, is investigated in the presence of the Rashba spin-orbit interaction in the theory of coherent quantum transport, which is presented by Mireles and Kirczenow within the Landauer framework of ballistic transport. Here GaAs acts as a quantum well while GaAlAs as a barrier, respectively.Firstly, the transmission coefficient as the function of the length of the barrier or that of the well is calculated in the F/SMW/F heterostructrues. The effect of resonant-tunnelling appears in the structure. Increasing the length of the barrier or that of the well under the different Rashba coupling strength, the results are written as follow:(1) Increasing the length of the well, the period of the transmission coefficient is not changed greatly, but the value of the transmission coefficient is changed obviously. The phase of the spin-down electrons moves so the phasic difference between the spin-up electrons and spin-down ones increases.(2) Increasing the length of the barrier, the period of the transmission coefficient is changed obviously, but the value of the transmission coefficient is not changed greatly. The phasic difference between the spin-up electrons and spin-down ones decreases.Then the transmission coefficient as the function of the Rashbacoupling strength is calculated in both the F/SMW/F heterostructures and the F/S/F heterostructures. Compared the results in the different heterostructures, the difference can be seen clearly. In the F/S/F heterostructures, the transmission coefficient against the coupling strength oscillates strongly, but the periodicity of the transmission coefficient becomes weakened than the one in the F/S/F heterostructures. The value of the polarization in the F/SMW/F structure proposed in this work, which can reach 60% or even more, is bigger than that of the F/S/F structure, and the polarization can be reversed when the strength of the spin-orbit coupling is adjusted in the F/SMW/F structure.These results show that the high coefficient of the spin injection can be found by adjusting the length of the SMW layer and the spin-orbit coupling strength. These help us deepen the understanding of spin polarized transport properties and give us another choice to realize a well-controlled spin-transistor device.