Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 13: Poster 1
HL 13.24: Poster
Montag, 26. März 2007, 15:00–17:30, Poster A
Magnetization measurements of low-dimensional electron systems by static and dynamic cantilever magnetometry — •A. Krohn1, J. I. Springborn1, N. Ruhe1, M. A. Wilde2, D. Heitmann1, and D. Grundler2 — 1Institut für Angewandte Physik, Universität Hamburg, Jungiusstrasse 11, 20355 Hamburg — 2Technische Universität München, Department E10, James-Franck-Strasse 1, 85748 Garching
A direct way to achieve information about the ground state of an electron system in semiconductors is to measure the magnetization M=−∂ F/∂ B (F is the free energy). We use a cantilever magnetometer based on a fiber-optics interferometer to study the magnetization of a two-dimensional electron system (2DES) at a temperature down to 0.3 K and a magnetic field B of up to 14.5 T. We apply two different modi simultaneously: The well established static measurement of M and a dynamic technique where we modulate the gate voltage applied to the 2DES. By the latter technique we detect ∂ M/∂ Ns (Ns is the carrier density). By the novel set-up we are thus able to compare the static magnetization and the dynamic susceptibility measured on the same 2DES. In our experiment we investigate a 2DES in an inverted high electron mobility transistor structure and monitor the de Haas-van Alphen oscillations by the two different techniques. The 2DES has a maximum carrier density of 6 · 1011 cm−2 and mobility of 45,000 cm2/Vs at 0.3 K. We find that the magnetic data agree within about 10%. We acknowledge financial support by the Deutsche Forschungsgemeinschaft via SFB508 and GR1640/1.