Münster 1999 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 39: Symposium: Quanten Hall Systeme
HL 39.6: Fachvortrag
Freitag, 26. März 1999, 12:00–12:30, H1
Magnetization of the Fractional Quantum Hall States — •D. Grundler1, I. Meinel1, T. Hengstmann1, D. Heitmann1, W. Wegscheider2, and M. Bichler2 — 1Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstr. 11, D-20355 Hamburg — 2Walter Schottky Institut, Technische Universität München, Am Coulombwall, D-85748 Garching
We report the observation of electron magnetism originating in a single–layered GaAs–heterojunction from the integer and fractional quantum Hall states. The studies were performed for temperatures between 0.3 K and 7 K on gated, high–mobility two–dimensional electron systems. The temperature dependence of the magnetization at the integer filling factor ν=1, i.e., the spin–polarized quantum Hall ferromagnetic state, shows a clear signature of low–lying collective spin–wave excitations. We also find oscillations in the magnetic moment at various fractional filling factors, both for ν<1 and ν>1, which persist up to 4 K. Most prominent features are found at 1/3, 2/3, 4/5 and 8/5. Surprisingly, an intrinsic strongly asymmetric magnetization around ν=1 is observed. All these experimental findings show that the magnetization of a high–mobility two–dimensional electron system within the magnetic quantum limit is strongly governed by electron–electron interactions and the related ground state energy renormalization effects.
Financial support by the DFG via the Sonderforschungsbereich SFB 508 ’Quantenmaterialien’ is ackknowledged.