Formation of islands of condensed exciton phases in semiconductor quantum wells in inhomogeneous fields

Sugakov, V. I.; Chernyuk, A. A.

doi:10.1134/s0021364007110094

Cited by 16 publications

(28 citation statements)

References 6 publications

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“…Just in the form of (2.15), we investigated a spatial distribution of the exciton density at exciton condensation using the spinodal decomposition approximation by choosing different dependencies f on n [21,23,25]. Thus, our previous consideration of the problem corresponds to the diffusion movement of hydrodynamic equations (2.1), (2.7).…”

Section: -3mentioning

confidence: 99%

“…Our model is based on the appearance of self-organization processes in non-equilibrium systems for excitons with attractive interaction shown in [2,3]. Investigations performed in this model [19][20][21][22][23][24][25] gave the explanations of spatial structures and their temperature and pumping dependencies obtained in different experiments [4,5,[8][9][10]. Theoretical approaches of the works [19][20][21][22][23][24][25] are based on the following assumptions.…”

Section: Introductionmentioning

confidence: 99%

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Exciton condensation in quantum wells. Exciton hydrodynamics. The effect of localized states

Sugakov¹

2014

Condens. Matter Phys.

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The hydrodynamic equations for indirect excitons in the double quantum wells are studied taking into account 1) a possibility of an exciton condensed phase formation, 2) the presence of pumping, 3) finite value of the exciton lifetime, 4) exciton scattering by defects. The threshold pumping emergence of the periodical exciton density distribution is found. The role of localized and free exciton states is analyzed in the formation of emission spectra.

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Section: -3mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exciton condensation in quantum wells. Exciton hydrodynamics. The effect of localized states

Sugakov¹

2014

Condens. Matter Phys.

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“…In the previous studies of the condensed phase, two popular models of the phase transitions were used. We applied the stochastic model of the nucleation-growth (Livshits-Slyosov) in the works 6,8,17 and the model of spinodal decomposition (Kahn-Hillert) in the works 9,16,19,[27][28][29] , modified and generalized for a system of particles with a finite lifetime. For the solution of the problem of the present paper, we applied a modified model of spinodal decomposition.…”

Section: Model Of the System Basic Equationsmentioning

confidence: 99%

“…32 . The model of the phase transitions of particles with a finite lifetime successfully managed to describe 6,9,16,17,19,[27][28][29] the emission from the ring around the laser spot, observed in Ref. 2 , the emission from the quantum well under the aperture in the electrode, observed in Refs.…”

Section: Introductionmentioning

confidence: 99%

Model of fragmentation of the exciton inner ring in semiconductor quantum wells

2014

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The appearance of the non-homogeneous structures of the indirect exciton density distribution in the region of the quantum well (in the region of the inner ring) is explained. The structure (the fragmentation) occurs due to the exciton condensed phase formation because of interaction between excitons. The formation of the structure is related with the non-equalibrity of the system, which is caused by the exciton finite lifetime and the presence of the pumpimg. The structure emerges in the shape of a set of islands or circles of the condensed phase. The structure type depends on the pumping intensity, the size of the laser spot and disappears with increasing the temperature. The merging of two structures, created by different laser spots, is investigated at decreasing the distance between the centers of the spots.

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“…Photoexcitation of excitons and luminescence registration was performed through the circular window of ø5 µm size in a metal mask (Schottky gate). Dipolar excitons were collected in a ring lateral trap which arose along the window perimeter because of strongly non-uniform electric field [11,12]. An increased image of the window was projected on an entrance slit of a spectrometer supplied with a cooled silicon CCD camera.…”

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confidence: 99%

Two-photon correlations of luminescence at the Bose-Einstein condensation of dipolar excitons

et al. 2009

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Correlations of luminescence intensity (a 2 nd order correlator g (2) (τ ), where τ is the delay time between photons in registered photon pairs) have been studied under Bose-Einstein condensation of dipolar excitons in the temperature range of 0.45÷4.2 K. Photoexcited dipolar excitons were collected in a lateral trap in GaAs/AlGaAs Schottky-diode heterostructure with single wide (25 nm) quantum well under electric bias applied between heterolayers. Two-photon correlations were measured with the use of a classical Hanbury Brown-Twiss two-beam intensity interferometer with the time resolution of ≈ 0.4 ns. Photon "bunching" has been observed near the Bose condensation threshold of dipolar excitons that was determined by the appearance of a narrow luminescence line of exciton condensate at optical pumping increase (FWHM of the narrow line at the threshold 200 µeV). The two-photon correlation function shows super-poissonian distribution, g (2) (τ ) > 1, at time scales of system coherence (τc 1 ns). No photon bunching was observed with the used time resolution at the excitation pumping appreciably below the condensation threshold. At excitation pumping well above the threshold, when the narrow line of exciton condensate begins to grow in the luminescence spectrum, the photon bunching is decreasing and finally vanishes with further excitation power increase. In this pumping range, the photon correlation distribution becomes poissonian reflecting the single-quantum-state origin of excitonic Bose condensate. Under the same conditions a first-order spatial correlator, g (1) (r), measured by means of the luminescence amplitude interference from spatially separated condensate parts under cw photoexcitation, remains significant on spatial scales around 4 µm. The discovered effect of photon bunching is rather temperature-sensitive: it drops several times with temperature increase from 0.45 K up to 4.2 K. If we assume that the luminescence of dipolar excitons collected in the lateral trap reflects directly coherent properties of interacting exciton gas, the observed phenomenon of photon bunching nearby condensation threshold -where exciton density and hence luminescence intensity fluctuations are most essential -manifests phase transition in interacting exciton Bose gas. It can be used as an independent tool for exciton Bose condensation detection.

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Formation of islands of condensed exciton phases in semiconductor quantum wells in inhomogeneous fields

Cited by 16 publications

References 6 publications

Exciton condensation in quantum wells. Exciton hydrodynamics. The effect of localized states

Exciton condensation in quantum wells. Exciton hydrodynamics. The effect of localized states

Model of fragmentation of the exciton inner ring in semiconductor quantum wells

Two-photon correlations of luminescence at the Bose-Einstein condensation of dipolar excitons

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