Spin–orbit interactions in high In-content InGaAs/InAlAs inverted heterojunctions for Rashba spintronic devices

We have studied molecular beam epitaxy growth and magneto-transport of novel InxGa1−xAs/InxAl1−xAs (x=0.5 and 0.75) inverted modulation-doped heterojunctions. Large Rashba-type spin–orbit coupling constants, α∼20×10−12 eV m, as well as high two-dimensional electron mobilities, μe∼2×105 cm2/V s, have been confirmed at ∼1.5 K. It was also found that larger α’s were confirmed in the higher In-content heterojunctions with thinner InGaAs surface channel. These results are qualitatively explained by the differences in the energy bandgap, the electron effective mass, and the mean electric field strength at the heterojunction interface. The above features of α and μe, seem to be promising in the applications in the spintronic devices as well as in the mesoscopic structures for novel spin physics based on the Rashba spin–orbit interaction.