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By placing the biased tip of an atomic force microscope at a specific position above a semiconductor surface we can locally shape the potential landscape. Inducing a local repulsive potential in a two-dimensional electron gas near a quantum point contact, one obtains a potential minimum which exhibits a remarkable behavior in transport experiments at high magnetic fields and low temperatures. In such an experiment, we observe distinct and reproducible oscillations in the measured conductance as a function of magnetic field, voltages, and tip position. They follow a systematic behavior consistent with a resonant tunneling mechanism. From the periodicity in the magnetic field we can find the characteristic width of this minimum to be of the order of 100 nm. Surprisingly, this value remains almost the same for different values of the bulk filling factors, although the tip position has to be adjusted by distances of the …
American Physical Society
Publication date: 
9 Jun 2014

Nikola Pascher, Flavia Timpu, Clemens Rössler, Thomas Ihn, Klaus Ensslin, Christian Reichl, Werner Wegscheider

Biblio References: 
Volume: 89 Issue: 24 Pages: 245408
Physical Review B