Regensburg 2004 – scientific programme
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HL: Halbleiterphysik
HL 14: Symposium Quanten-Hall-Systeme
HL 14.3: Talk
Tuesday, March 9, 2004, 11:15–11:45, H15
Optical Probe of Fractionally-Charged Quasiholes — •C. Schüller1, K.-B. Broocks1, P. Schröter1, Ch. Heyn1, D. Heitmann1, T. Chakraborty2, V. M. Apalkov3, M. Bichler4, and W. Wegscheider5 — 1Institut für Angewandte Physik, Universität Hamburg — 2Institute for Mathematical Sciences, Chennai, India — 3University of Utah, Salt Lake City, USA — 4Walter-Schottky-Institut, Garching — 5Institut für Experimentelle und Angewandte Physik, Universität Regensburg
We perform optical experiments on dilute two-dimensional electron systems (2DES) at very low temperatures (T<0.1 K) and high magnetic fields [1]. In photoluminescence experiments on a 2DES subjected to a quantizing magnetic field around ν=1/3, we have observed an anomalous dispersion of the charged excitons [2]. We have found that the anomaly exists only at a very low temperature (0.1 K) and an intermediate electron density (0.9×1011 cm−2). It is explained to occur due to the perturbation of the incompressible liquid at ν=1/3. The perturbation is induced by the close proximity of a localized charged exciton which creates a fractionally-charged quasihole in the liquid [3]. The intruiging experimentally observed puzzle that the anomaly (2 meV) can be destroyed by applying a small thermal energy of ∼ 0.2 meV is thereby resolved, as this energy is enough to close the quasihole energy gap. This work presents a probe of the quasihole gap in a quantum Hall system.
[1] C. Schüller et al., Phys. Rev. B 65, 081301(R) (2002).
[2] K.-B. Broocks et al., Phys. Rev. B 66, 041309(R) (2002).
[3] C. Schüller et al., Phys. Rev. Lett. 91, 116403 (2003).