Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 14: Symposium Quanten-Hall-Systeme

HL 14.3: Vortrag

Dienstag, 9. März 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).