Spin–Orbit Interaction in ZnO/MgxZn1 – xO Heterojunctions Probed by Electron Spin Resonance Spectroscopy

The spin–orbit interaction in a series of ZnO/MgxZn1 – xO heterojunctions containing a two-dimensional electron system with a wurtzite structure has been studied in detail. The spin–orbit coupling constants have been determined from the analysis of the modification of the single-particle g-factor caused by the spin–orbit interaction in the quantum Hall effect regime. The g-factor has been measured with high accuracy by the electron paramagnetic resonance technique in wide ranges of magnetic fields and electromagnetic frequencies. The spin–orbit coupling constants have been determined for a series of samples with different Mg concentrations, which has allowed us to obtain the dependence of the spin–orbit coupling constant on the two-dimensional electron density n. The measured spin–orbit coupling constant is in the range of 0.5–0.8 meV Å and quite weakly depends on n. The coefficients specifying the linear and cubic contributions to the spin–orbit interaction determined from the approximation of the experimental data are α0 = 0.48 meV Å and γ = 0.12 eV Å3, respectively. These values are correlated with results obtained by other research groups.