THE MAGNETIC-FIELD DEPENDENT CHARACTERISTICS OF CONDUCTANCE FLUCTUATIONS IN BALLISTIC QUANTUM DOTS

We study magneto-resistance fluctuations in GaAs/AlGaAs, ballistic quantum dots. At low temperatures, and at sufficiently low magnetic fields, the fluctuations obscure any average features in the magneto-resistance. As the magnetic field is increased, such that the cyclotron orbit size becomes much smaller than the dot dimensions, however, a strong decay in their high frequency content is observed. We associate this behaviour with the formation of well defined edge states in the dot, and in order to account for our observations apply a simple model, which considers the flux enclosed by skipping orbits localised at the dot walls.