MAGNETOTRANSPORT IN HEXAGONAL AND RECTANGULAR ANTIDOT LATTICES

In order to investigate anisotropic transport in various types of lattices, two-dimensional electron gas in the hexagonal and rectangular antidot lattices are measured. Magnetoresistance is isotropic in hexagonal lattice, but anisotropic in the rectangular lattice with circular antidots. The influence of antidot shapes upon anisotropic transport is also investigated in the rectangular lattice. It is found that the anisotropic transport is sensitive to the arrangement and the shape of antidot potential and anomalous peaks are observed in rectangular lattice with ellipsoidal antidots. The origin of the anomalous peaks is discussed. In both lattices quenching of the flail effect is observed and the positions of commensurate peaks in Hall resistance shift to higher field than that in magnetoresistance. These effects cannot be explained by the pinned orbit model.