Crystallographic plane tuning of magnetoplasmon excitations in two-dimensional electron gas systems.

We investigate theoretically the magnetoplasmon spectrum of two-dimensional electron gas systems grown along different crystallographic directions, which are modulated by both the Dresselhaus spin-orbit interaction (DSOI) and the Rashba spin-orbit interaction (RSOI). Because the DSOI depends on the crystallographic orientation, the magnetoplasmon spectrum in the presence of the DSOI shows distinct features for different crystallographic planes. For some high-index planes, such as (140) and (114), the magnetoplasmon spectrum is anisotropic even under the pure-DSOI modulation, which is different from the isotropic behavior for the high-symmetry (001) plane. The coexistence of the DSOI and the RSOI leads to more drastic variations of the anisotropic magnetoplasmon spectrum in different crystallographic planes, which are revealed from the splittings of the collective excitation modes and the intensity of the spin density excitation at the anticrossing center of the splittings.