Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65
MA 20.29: Poster
Montag, 7. März 2005, 14:00–18:00, Poster TU C
Piezo-controlled cantilever magnetometer for de Hass-van Alphen effect studies on MnAs — •O. Rösler1, A. Krohn1, M. Wilde1, J.I. Springborn1, D. Grundler1, Ch. Heyn1, D. Heitmann1, L. Däweritz2, K.J. Friedland2, and K.H. Ploog2 — 1Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg — 2Paul Drude Institut für Festkörperelektronik, Hausvogteiplatz 5 - 7, 10117 Berlin
Measuring the de Haas-van Alphen (dHvA) effect in a ferromagnetic thin film by means of a torque magnetometer is a challenging task. The spontaneous spin magnetization might induce such a large torque that the inherent high sensitivity of the magnetometer degrades significantly at high magnetic field B. We have realized a micromechanical cantilever magnetometer (MCM) with a piezo-controlled capacitance readout which circumvents the problem. Using the MCM, we first measured the hysteretic ferromagnetic behavior of an epitaxial MnAs layer at B < 3 T. Second, the large MCM deflection was compensated at B = 3 T using a piezoceramics-based walker. With the optimized configuration, we then measured the dHvA effect up to 15 T and down to 270 mK. Temperature-dependent data obtained at different tilt angles revealed an anisotropic Fermi surface and an anisotropic effective mass of the electrons. The absolute value was near the free-electron mass. We acknowledge financial support by the BMBF via 13N8283 "Spintronik" and by the DFG via SFB508 and Gr1640/1-2.