WEAK-LOCALIZATION IN CHAOTIC VERSUS NONCHAOTIC CAVITIES - A STRIKING DIFFERENCE IN THE LINE-SHAPE

We report experimental evidence that chaotic and nonchaotic scattering through ballistic cavities display distinct signatures in quantum transport. In the case of nonchaotic cavities, we observe a linear decrease in the average resistance with magnetic field which contrasts markedly with a Lorentzian behavior for a chaotic cavity. This difference in line shape of the weak-localization peak is related to the differing distribution of areas enclosed by electron trajectories. In addition, periodic oscillations are observed which are probably associated with the Aharonov-Bohm effect through a periodic orbit within the cavities.