Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 35: Transport: Nanoelectronics I - Quantum Dots, Wires, Point Contacts 3

TT 35.10: Talk

Thursday, February 28, 2008, 16:30–16:45, H 3010

Effect of Magnetic field on edge channel interference in an electronic Mach-Zehnder interferometer — •Leonid Litvin, Andreas Helzel, Peter Tranitz, Werner Wegscheider, and Christoph Strunk — Institute of experimental and applied physics, University of Regensburg, D-93040 Regensburg, Germany

We study an electronic Mach-Zehnder Interferometer (MZI) employing the edge channels of a two-dimensional electron gas in the quantum Hall regime and quantum point contacts as tuneable beam splitters. In this system interference contrast up to 80% can be achieved at low temperatures. Two interferometers with the arm length of 14 and 9 µm were investigated. We found that the interference contrast depends strongly on interferometer size and filling factor. High visibility is restricted to a rather small interval of magnetic field, which approximately ranges from filling factor 2 to 1, with maximum near 1.5. The temperature dependences of visibility taken at fixed magnetic field show exponential damping above ≈45 mK. Below this value the visibility has much weaker T-dependence. This implies that two energy scales are responsible for the decay of visibility.