Fractal Conductance Fluctuations in Hard-wall' InGaAs/InP Billiards
Abstract
The use of surface-gate designs to define ballistic devices in the two-dimensional electron gas of AlGaAs/GaAs heterostructures has led to the observation of a spectacular variety of novel physics phenomena. However, almost fifteen years on from the first observation of ballistic conduction in such devices, fundamental aspects of their behavior remain unresolved. Recent experiments identified fractal conductance fluctuations (FCF) as a generic property of quantum electron transport through soft-walled' billiards defined by parabolic energy profiles. Here we show that this fractal phenomenon is also observed in InGaAs/InP billiards. Our measurements show that the InGaAs/InP billiards are defined by hard' walls with an energy profile an order of magnitude steeper than for AlGaAs/GaAs billiards. These observations contradict current semi-classical models of ballistic transport, which predict a critical sensitivity of quantum ballistic phenomena to the precise profile of the billiard walls. We also show that the FCF in the two billiard systems display an identical dependence on parameters that determine the electron phase coherence, further emphasizing the generic character of this unexplained fractal conduction phenomenon.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2003
- Bibcode:
- 2003APS..MARA23008M