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.