Single-particle relaxation times in antidot arrays

Magnetotransport in GaAs/Ga1−xAlxAs heterostructures with a square array of antidots has been investigated. Single-particle relaxation times τs are estimated from the amplitudes of Shubnikov–de Haas oscillations and two values of τs are found at low and high magnetic fields. The critical field at which τs changes corresponds to the magnetic field where the cyclotron diameter 2Rc is almost equal to the effective constriction length Lc between two antidots. This suggests that the influence of scattering from antidots on τs is different in the region where 2Rc>Lc and where 2Rc<Lc.