Highly anisotropic commensurability oscillations in two-dimensional holes at the GaAs/AlGaAs (3 1 1)A interface

Measurements of commensurability oscillations in GaAs/AlGaAs two-dimensional (2D) hole systems grown on GaAs (3 1 1)A substrates reveal a remarkable anisotropy: the amplitude of the measured commensurability oscillations along the [2̄ 3 3] direction is about 100 times larger than along [0 1 1̄]. For 2D electron systems at similar interfaces, however, we observe nearly isotropic oscillations, suggesting that the anomalous anisotropy is intrinsic to GaAs 2D holes at the (3 1 1)A interface.