Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 101: Transport - Poster Session

TT 101.4: Poster

Thursday, April 3, 2014, 15:00–19:00, P2

Electronic current switching at finite temperature by magnetic focusing in a soft-wall quantum dot — •Christian Morfonios and Peter Schmelcher — Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany

We demonstrate a mechanism enabling efficient switching of the finite-temperature magnetoconductance in an electronic quantum dot with designed soft-wall confinement. The mechanism relies on the effective increase of the available area of motion within the dot with increasing energy, so that the magnetically deflected electron density retains invariant spatial characteristics at an optimal low field strength. Heavily suppressed background transmission can then be achieved along the entire ground propagation channel of the incoming electrons, while resonant states couple very weakly to the attached leads, even for a large number of dot levels. The presence of soft walls in an elliptically shaped quantum dot simultaneously aids collimated electron transport and high transmission for zero field, leading to efficient finite-temperature magnetoconductance switching at linear response. The effect is investigated in terms of the influence of the width of the soft wall and its profile at given temperatures, as well as for arrays of connected dots.