Dresselhaus spin-orbit interaction in p-AlGaAs/GaAs/AlGaAs square quantum well

The effect of spin-orbit interaction was studied in a high-quality p-AlGaAs/GaAs/AlGaAs square quantum well using the surface acoustic wave (SAW) technique in the frequency range 30 MHz – 300 MHz, at temperatures 20 mK – 300 mK, in the magnetic field of up to 18 T and at various acoustic intensities. The structure grown on a GaAs (100) substrate was symmetrically doped with carbon on both sides of the well and had hole concentration p = 1.2 10¹¹ cm⁻² and mobility μ = 1.8 10⁶ cm²/V s at 300 mK. The attenuation and relative velocity of SAW were measured and then the complex ac conductance was calculated. At low magnetic fields B < 2 T observed Shubnikov–de Haas-type oscillations of the ac conductance undergo beatings induced by a spin-orbit interaction. Applying the fast Fourier transform analysis we separated the conductance contributions from the two heavy hole subbands split by the spin-orbit interaction. For each of the subbands the values of the effective masses and quantum relaxation times have been computed, and then the energy of the spin-orbit interaction Δ_SO  = (0.18 +/- 0.05) meV was obtained. We concluded that the spin-orbit splitting is governed by the Dresselhaus mechanism due to the small magnitude of the spin-orbit interaction and to the square quantum well profile.