Micron-sized loops of high-mobility two-dimensional electron gas have been made on GaAs-AlGaAs heterostructures using a novel split-gate technique. Aharonov-Bohm oscillations of amplitude up to 20% of the device resistance have been observed at very low temperatures (T<100 mK), together with h/2e oscillations which appear to be due to interference between pairs of time-reversed paths near B=0. The h/e period is found to vary by ∼25% with magnetic field, possibly as a result of the formation of edge states. In the quantum Hall effect, plateaus in Rxx are seen at high B due to variations in carrier concentration across the ring, which may cause backscattering of some edge states.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)