Hamburg 2001 – scientific programme
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HL: Halbleiterphysik
HL 15: Quanten-Hall-Effekt
HL 15.10: Talk
Tuesday, March 27, 2001, 12:45–13:00, S16
Temperature dependence of the de Haas-van Alphen-effect in a two-dimensional electron system — •Markku Schwarz, Dirk Grundler, Sönke Groth, Marc Wilde, Christian Heyn, and Detlef Heitmann — Institut of Applied Physics, University of Hamburg
Using a micromechanical cantilever magnetometer we have investigated the
de Haas-van Alphen(dHvA)-effect of a two-dimensional electron system (2DES) in the integer quantum Hall effect regime. The dHvA-oscillation amplitude Δ M at integer filling factors and its temperature dependence provides important information about the energy gaps in the ground state energy spectrum of the 2DES. At large even filling factors ν ≥ 6 we find an excellent agreement with the temperature dependence expected from the Lifshitz-Kosevich theory. This shows that the relevant energy separation Δ E entering the level statistics is given by the Landau quantization energy ℏ ωc. The energy gap calculated from the amplitude Δ M according to the thermodynamic relation Δ E = B × Δ M(T=0) is
different. Here, the measured value is reduced by level-broadening. The enlargement of Δ M observed in high magnetic fields, especially at odd filling factors, is attributed to electron-electron interaction. We acknowlegde financial support from the DFG via the ”Schwerpunktprogramm Quanten-Hall-Systeme”.
[1] M. P. Schwarz, D. Grundler, I. Meinel, Ch. Heyn, and D. Heitmann, Apl. Phys. Lett 76, 3564 (2000)