Quantum Transport in one Dimensional GaAs-AlGaAs Microstructures.

We have observed the Aharonov-Bohm effect in the magnetoresistance of doubly connected geometries fabricated in high mobility GaAs/AlGaAs heterostructures. The periodic oscillations in the resistance associated with magnetic flux hc/e, hc2e, and hc3e penetrating the annulus are suppressed above w sub c tau ~ 10, where w sub c is the cyclotron frequency and tau is the scattering time corresponding to squrt (eH/hc~W/2) where W is the wire comprising the annulus. Fluctuations in the resistance as a function of magnetic field are observed for 0