Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 75: Transport: Spintronics and magnetotransport 1 (TT, jointly with HL, MA)
HL 75.11: Vortrag
Donnerstag, 14. März 2013, 12:15–12:30, H18
Magnetotransport along a boundary: From coherent electron focusing to edge channel transport — •Thomas Stegmann, Dietrich E. Wolf, and Axel Lorke — University of Duisburg-Essen, Department of Physics and CENIDE
In a two dimensional electron system with a boundary, electrons are injected at one point on the boundary and focussed by a perpendicular magnetic field B onto another voltage probe on the boundary. Using the nonequilibrium Green’s function approach we study theoretically the 4-point Hall resistance Rxy as a function of B. For low fields, Rxy shows the characteristic equidistant peaks observed in the experiment, which can also be explained by simple classical trajectories: The electrons are guided on cyclotron orbits, are reflected speculary at the boundary, and end finally at the collector when a multiple of the cyclotron diameter equals the distance between injector and collector. In a strong magnetic field, the current is carried by edge channels parallel to the boundary and the typical fingerprint of the quantum Hall effect is observed. Here, we study the transition from the classical cyclotron motion to the edge channel transport and discuss its influence on the focussing spectrum. In intermediate fields, we find that Rxy shows sets of oscillations, which are neither periodic in B (such as the magnetic focussing peaks) nor in 1/B (quantum Hall effect). These oscillations can be understood as interference between adjacent edge states.