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HL: Halbleiterphysik
HL 24: Transporteigenschaften
HL 24.2: Talk
Wednesday, March 29, 2000, 16:15–16:30, H14
Transmission of 2D electrons through magnetic barriers — •Volker Kubrak1, Andreas Neumann1, Bryan Gallagher1, Peter Main1, David Sherwood1, Mark Fromhold1, Chris Marrows2, and Bryan Hickey2 — 1School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, GB — 2Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, GB
We discuss experimental and theoretical results from hybrid magnet/semiconductor devices in which the stray field of a ferromagnetic element on the surface acts as a magnetic barrier for the near-surface 2DEG. The electron trajectories are curved in the region where the perpendicular component of the stray field is large. This hinders the traversal of that region. The barrier amplitude is tuned by changing the magnetisation of the element with an in-plane external magnetic field. As the barrier amplitude increases, fewer electrons can traverse the barrier, and the longitudinal resistance of the 2DEG enhances. The barrier can be "transparent" (low amplitude, most electrons transmitted) or "opaque" (large amplitude, all ballistic electrons classically reflected). We find the resistance enhancement due to a transparent barrier is independent of temperature (ballistic transmission) whereas that due to an opaque barrier decreases with temperature, indicating the importance of scattering for the transmission.