Regensburg 2000 – scientific programme

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HL: Halbleiterphysik

HL 17: Symposium: Der Quanten-Hall-Effekt wird 20 (II)

HL 17.1: Fachvortrag

Tuesday, March 28, 2000, 15:00–15:30, H15

Magneto-optical probe of the electron-electron interaction in the Quantum Hall systems — •I.V. Kukushkin^1,2, J. H. Smet¹, K. v. Klitzing¹, and K. Eberl¹ — ¹Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany — ²Institute of Solid State Physics, RAS, Chernogolovka, 142432 Russia

Time-resolved magneto-luminescence and inelastic light scattering techniques were used to study correlation effects in the two-dimensional electron system under the conditions of the Integer and Fractional Quantum Hall Effect (QHE).
From the magnetic field dependence of the first moment of luminescence line we derive values both for the Integer and Fractional QHE energy gaps. Inelastic light scatering technique was used to measure directly the Coulomb energy from the spin-flip cyclotron modes.
From the degree of circular polarization of the time-resolved radiative recombination of 2D-electrons with photo-excited holes bound to acceptors we have measured the magnetic field dependencies of the electron spin polarization for various fractional and Composite Fermions (CFs) states. The Fermi energy and the Zeeman splitting of CFs are measured from the temperature dependence of the electron spin polarization at ν =1/2. We demonstrate that the Zeeman splitting of CFs is enhanced by a factor of 2.5 due to the interaction between CFs, which is found to be very sensitive to a width of the 2D-channel. It is shown that the temperature dependence of the electron spin polarization measured at ν =1/3 has the activated behavior and the derived spin-wave energy gaps are compared with simultaneously measured transport values.