Optical detection of the integer and fractional quantum Hall effects in GaAs

Turberfield, Andrew J.; Haynes, Simon; Wright, Paul A.; Ford, Rebecca; Clark, Robert G.; Ryan, J.F.; Harris, J. J.; Foxon, C.T.

doi:10.1103/physrevlett.65.637

Cited by 250 publications

(107 citation statements)

References 10 publications

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“…The past decades have shown that optical experiments, like photoluminescence (PL) spectroscopy, can provide further and in some sense complementary information about the ground state of quantum Hall systems [1][2][3][4][5][6][7][8][9]. In fact, in optical experiments one is able to probe the bulk of a quantum Hall system, whereas transport is mostly governed by edge channels.…”

Section: Introductionmentioning

confidence: 99%

Charged Excitons in the Quantum Hall Regime

et al. 2004

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We review our recent optical experiments on two-dimensional electron systems at temperatures below 1 K and under high magnetic fields. The two-dimensional electron systems are realized in modulation-doped GaAsAlGaAs single quantum wells. Via gate electrodes the carrier density of the two-dimensional electron systems can be tuned in a quite broad range between about 1 × 10 10 cm −2 and 2 × 10 11 cm −2 . In dilute two-dimensional electron systems, at very low electron densities, we observe the formation of negatively charged excitons in photoluminescence experiments. In this contribution we report about the observation of a dark triplet exciton, which is observable at temperatures below 1 K and for electron filling factors < 1/3, i.e., in the fractional quantum Hall regime only. In experiments where we have increased the density of the two-dimensional electron systems so that a uniform two-dimensional electron system starts to form, we have found a strong energy anomaly of the charged excitons in the vicinity of filling factor 1/3. This anomaly was found to exist in a very narrow parameter range of the density and temperature, only. We propose a model where we assume that localized charged excitons and a uniform Laughlin liquid coexist. The localized charged exciton in close proximity to the Laughlin liquid leads to the creation of a fractionally-charged quasihole in the liquid, which can account for the experimentally observed anomaly.

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Section: Introductionmentioning

confidence: 99%

Charged Excitons in the Quantum Hall Regime

et al. 2004

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“…24 Unless d is smaller than the magnetic length λ, the PL spectra of such bilayer systems show no recombination from X − states. Instead, they show anomalies [1][2][3][4][5][6][7] at the filling factors ν = 1 3 and 2 3 at which Laughlin incompressible fluid states 39 are formed in the 2DEG and the fractional quantum Hall (FQH) effect 40 is observed in transport experiments. The present paper is a continuation of our earlier work 29 where we studied the energy spectra of 2D fractional quantum Hall systems in the presence of an optically injected valence hole.…”

Section: Introductionmentioning

confidence: 99%

“…The optical properties of quasi-two-dimensional (2D) electron systems in high magnetic fields have been extensively studied in the recent years both experimentally [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and theoretically. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] In symmetrically doped quantum wells (QW), where both conduction electrons and valence holes are confined in the same 2D layer, the photoluminescence (PL) spectrum of an electron gas (2DEG) probes the binding energy and optical properties of neutral and charged excitons (bound states of one or two electrons and a hole, X = e-h and X − = 2e-h), rather than the original correlations of the 2DEG itself.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence from fractional quantum Hall systems: Role of separation between electron and hole layers

Wójs

Quinn

2000

Phys. Rev. B

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The photoluminescence (PL) spectrum of a two-dimensional electron gas (2DEG) in the fractional quantum Hall regime is studied as a function of the separation d between the electron and valence hole layers. The abrupt change in the response of the 2DEG to the optically injected hole at d of the order of the magnetic length λ results in a complete reconstruction of the PL spectrum. At d < λ, the hole binds one or two electrons to form neutral (X) or charged (X − ) excitons, and the PL spectrum probes the lifetimes and binding energies of these states rather than the original correlations of the 2DEG. At d > 2λ, depending on the filling factor ν, the hole either decouples from the 2DEG to form an "uncorrelated" state h or binds one or two Laughlin quasielectrons (QE) to form fractionally charged excitons hQE or hQE2. The strict optical selection rules for bound states are formulated, and the only optically active ones turn out to be h, hQE* (an excited state of the dark hQE), and hQE2. The "anyon exciton" hQE3 suggested in earlier studies is neither stable nor radiative at any value of d. The critical dependence of the stability of different states on the presence of QE's in the 2DEG explains the observed anomalies in the PL spectrum at ν =

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“…There have been many experimental studies of photoluminescence (PL) in fractional quantum Hall systems during the past decade (Heiman et al 1988, Turberfield et al 1990, Goldberg et al 1990, Buhmann et al 1990, Goldys et al 1992, Kukushkin et al 1994, Takeyama et al 1998, Gravier et al 1998, Kheng et al 1993, Shields et al 1995, Finkelstein et al 1995, Hayne et al 1999, Nickel et al 1998, Tischler et al 1999, Wojtowicz et al 1999, Brown et al 1996, but the data have been rather difficult to interpret. In order to obtain a more complete understanding of the PL process, it is essential to understand the nature of the low-energy states of the electron-hole system, and to evaluate their oscillator strength for radiative recombination.…”

Section: Introductionmentioning

confidence: 99%

Energy spectra and photoluminescence of fractional quantum Hall systems containing a valence-band hole

Wójs

Quinn

2001

Philosophical Magazine B

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The energy spectrum of a two-dimensional electron gas (2DEG) interacting with a valence-band hole is studied in the high magnetic field limit as a function of the filling factor ν and the separation d between the electron and hole layers. For d smaller than the magnetic length λ, the hole binds one or more electrons to form neutral (X) or charged (X − ) excitons. The low-lying states can be understood in terms of Laughlin-like correlations among the constituent charged fermions (electrons and X − ). For d comparable to λ, the electron-hole interaction is not strong enough to bind a full electron, and fractionally charged excitons hQEn (bound states of a hole and one or more Laughlin quasielectrons, QE) are formed. The effect of these excitonic complexes on the photoluminescence spectrum is studied numerically for a wide range of values of ν and d.

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Optical detection of the integer and fractional quantum Hall effects in GaAs

Cited by 250 publications

References 10 publications

Charged Excitons in the Quantum Hall Regime

Charged Excitons in the Quantum Hall Regime

Photoluminescence from fractional quantum Hall systems: Role of separation between electron and hole layers

Energy spectra and photoluminescence of fractional quantum Hall systems containing a valence-band hole

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