Dresden 2006 – scientific programme
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HL: Halbleiterphysik
HL 9: Poster I
HL 9.58: Poster
Monday, March 27, 2006, 15:15–17:45, P3
Magnetic focusing phenomena in mesoscopic Hall-bar geometries — •Tobias Feil1, Kai Bröking2, Ragnar Fleischmann2, Werner Wegscheider1, and Dieter Weiss1 — 1Universität Regensburg, 93040 Regensburg — 2Max-Planck-Institut für Dynamik und Selbstorganisation, 37073 Göttingen
We investigate low field magnetotransport in ballistic Hall-bar geometries with dimensions much smaller than the electron mean free path at low temperatures. For the experiments we use GaAs/AlGaAs heterojunctions with mobilities up to 1000m2/Vs and a corresponding mean free path of 50µm. Our Hall-bars are manufactured by means of electron beam lithography and dry etching with typical potential probe separations between 2 and 10µm and potential probe width of ≈500nm.
Driving a constant current along the Hall-bar, we observe pronounced oscillations of the longitudinal resistance as a function of a perpendicular magnetic field. The oscillations, reminiscent of magnetic focusing, show minima with resistance values often below the Drude resistance. The experimental findings are compared to Landauer-Büttiker-type simulations, aiming at the transition from Drude resistance to ballistic transport in such mesoscopic Hall-bars.