Optical Detection of Integer and Fractional QHE in GaAs: Extension to the Electron Solid
Ten years on from the discovery of the integer QHE (IQHE) , and the subsequent discovery of condensation of electrons into an incompressible liquid — the fractional QHE (FQHE) , experiments are still largely restricted to electrical transport studies. Whilst there is a report of an optical measurement of the FQHE in a Si structure at 1.5K , optical experiments that probe the QHE in GaAs have remained a major challenge [4,5]. An important advance was made by the observation of anomalies in the energy of photoluminescence near v = 2/3 and v = 1 from a GaAs multiple quantum well at 0.4K . In this paper we report a definitive detection of both the integer and fractional QHE in GaAs, using intrinsic bandgap photoluminescence, by a study of integer states from v = 1 to 10 and of the v = 2/3 hierarchy out to the 5/9 daughter state, in an ultra-high mobility single heterojunction at 120mK . At higher fields the photoluminescence spectra are mapped out at 80mK through FQHE states of the v = 1/3 and 1/5 hierarchies. Of particular interest is a new photoluminescence peak that becomes clearly resolved in the region v < 1/5. The appearance of this peak at v ≃ 1/5 correlates with the rapid onset of a substantial non-linear out-of-phase conduction that has recently been shown to arise from threshold behaviour that may be associated with crystallisation [8, 9]. It also correlates in filling factor with the onset of a resonant radio-frequency absorption in this sample which maps out a phase boundary in the B-T plane .
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- 3.I.V. Kukushkin and V.B. Timofeev, Pis’ma Zh. Eksp. Teor. Fiz 44, 179 (1986) [JETP Lett. 44, 228 (1986)].Google Scholar
- 4.C.H. Perry, J.M. Worlock, M.C. Smith and A. Petrou, in: “High Magnetic Fields in Semiconductor Physics”, G. Landwehr, ed., Springer-Verlag, New York (1987), p202.Google Scholar
- 5.R. Stepniewski, W. Knap, A. Raymond, G. Martinez, T. Rötger, J.C. Maan and J.P. André, in: “High Magnetic Fields in Semiconductor Physics”, G. Landwehr, ed., Springer-Verlag, New York (1989), p62.Google Scholar
- 8.F.I.B. Williams, E.Y. Andrei, R.G. Clark; G. Deville, B. Etienne, C.T. Foxon, D.C. Glattli, JJ. Harris, E. Paris and P.A. Wright, in: “Localisation and Confinement of Electrons in Semiconductors”, G. Bauer, F. Kuchar and H. Heinrich, eds., Springer-Verlag, New York (1990), to be published.Google Scholar
- 9.F.I.B. Williams, G. Deville, E.Y. Andrei, D.C. Glattli, J.J. Harris, CT. Foxon, P.A. Wright, R.G. Clark, B. Etienne, O. Probst and C. Dorin, to be published.Google Scholar
- 11.P.A. Maksym, private communication.Google Scholar