%0 Journal Article
%T Electron focusing, mode spectroscopy and mass enhancement in small GaAs/AlGaAs rings
%A J Liu
%A K Ismail
%A KY Lee
%A JM Hong
%A S Washburn
%J Physics
%D 1992
%I arXiv
%R 10.1103/PhysRevB.47.13039
%X A new electron focusing effect has been discovered in small single and coupled GaAs/AlGaAs rings. The focusing in the single ring is attributed solely to internal orbits. The focusing effect allows the ring to be used as a small mass spectrometer. The focusing causes peaks in the magnetoresistance at low fields, and the peak positions were used to study the dispersion relation of the one-dimensional magnetoelectric subbands. The electron effective mass increases with the applied magnetic field by a factor of $50$, at a magnetic field of $0.5T$. This is the first time this increase has been measured directly. General agreement obtains between the experiment and the subband calculations for straight channels.
%U http://arxiv.org/abs/cond-mat/9208014v1