COHERENT ELECTRONIC BACKSCATTERING IN BALLISTIC MICROSTRUCTURES

A magnetoresistance peak at zero magnetic field due to coherent backsc attering is studied in submicrometer quantum dots with quantum-point-c ontact leads. A systematic series of experiments on ballistic microstr uctures shows that coherent backscattering is distinct from conductanc e fluctuations at finite fields and gives properties in agreement with semiclassical theory. The effect results from interference between pa irs of time-reversed paths of ballistic electrons scattered from the w alls of the dot, analogous to weak localization in diffusive systems.