Excitonic Instability and Electric-Field-Induced Phase Transition Towards a Two-Dimensional Exciton Condensate

Naveh, Y.; Laikhtman, B.

doi:10.1103/physrevlett.77.900

Cited by 86 publications

(73 citation statements)

References 12 publications

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“…15 In comparison to the HgTe/CdTe system, InAs/GaSb coupled quantum wells offer electric field tunability of the topological phase. 16 When the device size becomes smaller than the elastic mean free path (l e ), the transport properties are modified with respect to bulk samples. [17][18][19] As a consequence mesoscopic devices exhibit enhanced resistivity due to the lateral boundary scattering, studied extensively in narrow channels fabricated in GaAs two-dimensional electron gases (2DEGs).…”

Section: Introductionmentioning

confidence: 99%

Influence of etching processes on electronic transport in mesoscopic InAs/GaSb quantum well devices

et al. 2015

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We report the electronic characterization of mesoscopic Hall bar devices fabricated from coupled InAs/GaSb quantum wells sandwiched between AlSb barriers, an emerging candidate for two-dimensional topological insulators. The electronic width of the etched structures was determined from the low field magneto-resistance peak, a characteristic signature of partially diffusive boundary scattering in the ballistic limit. In case of dry-etching the electronic width was found to decrease with electron density. In contrast, for wet etched devices it stayed constant with density. Moreover, the boundary scattering was found to be more specular for wet-etched devices, which may be relevant for studying topological edge states.

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Section: Introductionmentioning

confidence: 99%

Influence of etching processes on electronic transport in mesoscopic InAs/GaSb quantum well devices

et al. 2015

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“…Recently, detailed numerical solutions of the BCS gap equation have been obtained for models of epitaxially grown double-layer structures. [10][11][12] We are interested in the high carrier density regime for which the underlying fermionic degrees of freedom of electrons and holes play an essential role in the pairing physics, and mean-field theory estimates of transition temperatures can be reliable. …”

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confidence: 99%

Engineering superfluidity in electron-hole double layers

1998

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We show that band-structure effects are likely to prevent superfluidity in semiconductor electron-hole double-layer systems. We suggest the possibility that superfluidity could be realized by the application of uniaxial pressure perpendicular to the electron and hole layers. ͓S0163-1829͑98͒51712-2͔The possibility of realizing a superconducting condensate of electron-hole pairs in a system consisting of two spatially separated layers of electrons and holes was suggested some time ago.1 Only recently, however, has it become feasible [2][3][4][5] to produce systems where the electrons and holes are close enough to interact strongly, and, at the same time, sufficiently isolated to inhibit optical recombination in nonequilibrium systems and tunneling between electron and hole bands. Since the overlap of the electron and hole wave functions in these systems can be made negligibly small, the joint motion of condensed electron-hole pairs turns out to be superfluid; antiparallel currents can flow in the two layers without dissipation. 1,6 Although the electron-hole condensation temperature has been predicted to be in an accessible range, and signatures of its occurrence have been discussed in the literature, 7,8 compelling evidence of a superfluid state is yet to appear. In this paper we propose a strategy for the realization of electron-hole superconductivity in double well systems. We point out that at high sufficiently densities, the anisotropy of the hole band in realistic wells is a major obstacle to the occurrence of superconductivity. We propose that the application of a moderate uniaxial stress (ϳ10 kbar) could reduce the anisotropy enough to permit the formation of a condensate.Microscopic theories of superfluidity in electron-hole liquids have usually been developed in the framework of a simple mean field theory 9 similar to the BCS theory of superconductivity. Recently, detailed numerical solutions of the BCS gap equation have been obtained for models of epitaxially grown double-layer structures. [10][11][12] We are interested in the high carrier density regime for which the underlying fermionic degrees of freedom of electrons and holes play an essential role in the pairing physics, and mean-field theory estimates of transition temperatures can be reliable. 13Indeed, recent variational 14 and diffusion 15 Monte Carlo calculations of the ground-state energy of an electron-hole double layer appear to qualitatively confirm BCS theory predictions for the dependence of the zero temperature gap on interlayer separation, provided that the attractive electronhole interaction is appropriately screened in estimating the BCS theory coupling constant. Although transition temperatures calculated with unscreened interactions ͑as high as 10 K with typical parameters͒ are expected to be overestimates, the naive expectation from these calculations is that the superfluid state should be within reach.An aspect of the problem which is potentially important at high densities, and to which little attention has been paid thus far, i...

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“…The tunneling between InAs and GaSb layers opens a mini hybridization gap, which was observed experimentally 11,12,13,14 . In addition, the electrons in GaSb can move across InAs/GaSb interface into InAs layer, forming a two-dimensional electron gas in InAs side and a two-dimensional hole gas in GaSb side, which is promising for observing the Bose-Einstein condensation of excitons 14,15,16 . In practical applications, there have been many proposals for electronic and optical devices utilizing the unique characteristics of InAs/AlSb/GaSb system such as resonant tunneling structures 17,18 , infrared detectors 19 , and interband cascade laser diodes 20 .…”

Section: Introductionmentioning

confidence: 99%

Spin states in InAs/AlSb/GaSb semiconductor quantum wells

Yang

Chang

2009

Phys. Rev. B

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We investigate theoretically the spin states in InAs/AlSb/GaSb broken-gap quantum wells by solving the Kane model and the Poisson equation self-consistently. The spin states in InAs/AlSb/GaSb quantum wells are quite different from those obtained by the single-band Rashba model due to the electron-hole hybridization. The Rashba spin-splitting of the lowest conduction subband shows an oscillating behavior. The D'yakonov-Perel' spin relaxation time shows several peaks with increasing the Fermi wavevector. By inserting an AlSb barrier between the InAs and GaSb layers, the hybridization can be greatly reduced. Consequently, the spin orientation, the spin splitting, and the D'yakonov-Perel' spin relaxation time can be tuned significantly by changing the thickness of the AlSb barrier.

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Excitonic Instability and Electric-Field-Induced Phase Transition Towards a Two-Dimensional Exciton Condensate

Cited by 86 publications

References 12 publications

Influence of etching processes on electronic transport in mesoscopic InAs/GaSb quantum well devices

Influence of etching processes on electronic transport in mesoscopic InAs/GaSb quantum well devices

Engineering superfluidity in electron-hole double layers

Spin states in InAs/AlSb/GaSb semiconductor quantum wells

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