Berlin 2005 – scientific programme
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HL: Halbleiterphysik
HL 16: Poster Ia
HL 16.24: Poster
Friday, March 4, 2005, 16:30–19:00, Poster TU E
Magnetic Focusing in Ballistic Hall-Bar Geometries — •Tobias Feil, Werner Wegscheider, and Dieter Weiss — Universität Regensburg
We investigate magnetotransport in Hall-bar geometries with dimensions much smaller than the electron mean free path at low temperatures. For the experiments we used GaAs/AlGaAs heterojunctions with low-temperature mobilities of 600 m2/Vs and a corresponding mean free path of 45 µm.
Hall-bars with typically 4 µm wide mesas and potential probe separation of 4 µm were defined by electron beam lithography and dry etching. By driving a constant current along the Hall-bar we observe, as a function of a perpendicular magnetic field, pronounced oscillations in the longitudinal voltage drop, with a periodicity given by the magnetic focus condition:
2nRC=L , n=1,2,3,...
with the cyclotron radius RC and the contact separation L.
The resistance minima of the oscillations are well below the Drude resistance at low temperatures.