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HL: Fachverband Halbleiterphysik

HL 13: Poster 1

HL 13.40: Poster

Montag, 26. März 2007, 15:00–17:30, Poster A

Magnetization of tunneling coupled double-layer quantum dots — •J. Topp¹, O. Roesler¹, D. Reuter², A.D. Wieck², D. Grundler³, and D. Heitmann¹ — ¹Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstraße 11, D-20355 Hamburg — ²Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum — ³Physik-Department E10, Technische Universität München, James-Franck-Straße 1, D-85747 Garching

We have experimentally investigated the magnetization M of large arrays of double-layer quantum dots. The dots were prepared from a modulation-doped AlGaAs/GaAs heterostructure containing two quantum wells separated by a 1 nm thick tunneling barrier. We used electron beam lithography and reactive ion etching to create a hexagonal-closed-packed array of up to 6·10⁶ dots with identical diameters of down to 300 nm. To investigate the magnetization M=−(∂ U/∂ B)_N,T (U is the inner energy and N the electron number) these dots were integrated to a micromechanical cantilever magnetometer operated at a temperature T=20 mK. Measuring M in magnetic fields B up to 16 T we have thereby monitored the electronic ground state energy U of double-layer quantum dots. From these data we extract the electron-electron interaction and tunneling-gap energy. The authors thank the Deutsche Forschungsgemeinschaft for financial support through SFB 508 and through the excellence cluster "Nanosystems Initiative Munich (NIM)".