Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 58: Poster IIb

HL 58.8: Poster

Dienstag, 8. März 2005, 16:30–19:00, Poster TU F

Interferometric cantilever magnetometer for de Haas-van Alphen effect studies — •N. Ruhe, J.I. Springborn, Ch. Heyn, D. Heitmann, and D. Grundler — Institut für Angewandte Physik, Uni Hamburg, Jungiusstr. 11, 20355 Hamburg

The magnetization M provides access to the ground state energy and electron-electron interaction of a two-dimensional electron system (2DES) [1]. At low temperature T and in a high magnetic field B, the de Haas-van Alphen effect occurs. We detect these oszillations by means of the torque M^→×B^→ acting on a quasistatic micromechanical cantilever magnetometer (MCM), which is made from a GaAs/AlGaAs heterostructure. The deflection of the flexible Cantilever is measured by a fiber-optics interferometer at T=300 mK up to B=15.5 T. The resolution of the interferometer is about 0.4 nm corresponding to a sensitivity of 2·10⁻¹⁴ J/T at B=10 T. In comparison to a capacitive read-out technique [1] the fiber-optics interferometer has the advantage that (i) a higher sensitivity might be reached and that (ii) electrical contacts and field-effect electrodes can be attached to the 2DES without degrading to the sensitivity. In current experiments we study the magnetization and magneto-transport simultaneously. Our latest results will be presented. We thank A. Schwarz for continuous support of the work and the DFG for financial support via GR1640/1 and via SFB508.

[1] M. Schwarz et al., Phys. Rev. B 65, 245315 (2002).