Cyclotron and electric-dipole spin resonances in a two-dimensional electron gas in the vicinity of the crossing of spin-split Landau levels

The fine structure of cyclotron (CR) and electric-dipole spin (EDSR) resonances in a heterostructure has been studied near the spin-split Landau-level crossing in a tilted magnetic field. Spin-orbit coupling splits the lines of the mixed CR-EDSR spectrum, the gaps being linear in the spin-orbit interaction. This effect is shown to be pronounced at the lowest Landau levels and sensitive to the magnetic-field orientation in the plane in the case of wide quantum wells. The polarization dependence of the EDSR efficiency far from the crossing region can help in distinguishing different spin-orbital terms in the effective two-dimensional Hamiltonian.