Conductance fluctuations in a quantum dot in the tunneling regime: Crossover from aperiodic to regular behavior

We discuss magnetoconductance fluctuations in a ∼ 1 microm GaAS/AlxGa1−xAs quantum dot in the shape of a chaotic stadium billiard with point contact leads. Here we emphasize measurements carried out in the tunneling regime, where each lead carries less than one fully conducting channel. We discuss various crossover phenomena as the magnetoconductance fluctuations evolve from aperiodic structure at low fields (B ≲ 0.5 T) into periodic, Aharonov-Bohm-like oscillations at higher fields.