Biexcitons in two-dimensional systems with spatially separated electrons and holes

Meyertholen, Andrew; Fogler, M. M.

doi:10.1103/physrevb.78.235307

Cited by 44 publications

(45 citation statements)

References 51 publications

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“…However, as shown previously [40][41][42] , at do0.87a e quantum exchange-correlation effects cause the change of repulsion to attraction leading to appearance of bi-excitons phases 12,39 . Narrow ranges of modulated phases (stripes, bubbles or supersolids) may exist near any of the first-order phase transition lines 43 .…”

Section: Methodsmentioning

confidence: 97%

High-temperature superfluidity with indirect excitons in van der Waals heterostructures

2014

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All known superfluid and superconducting states of condensed matter are enabled by composite bosons (atoms, molecules and Cooper pairs) made of an even number of fermions. Temperatures where such macroscopic quantum phenomena occur are limited by the lesser of the binding energy and the degeneracy temperature of the bosons. High-critical temperature cuprate superconductors set the present record of B100 K. Here we propose a design for artificially structured materials to rival this record. The main elements of the structure are two monolayers of a transition metal dichalcogenide separated by an atomically thin spacer. Electrons and holes generated in the system would accumulate in the opposite monolayers and form bosonic bound states-the indirect excitons. The resultant degenerate Bose gas of indirect excitons would exhibit macroscopic occupation of a quantum state and vanishing viscosity at high temperatures.

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Section: Methodsmentioning

confidence: 97%

High-temperature superfluidity with indirect excitons in van der Waals heterostructures

2014

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“…This is not an artifact of the extrapolation, which followed the scheme set out in Ref. 21, for we were able to find points with nonzero binding energies outside the region of stability defined by Meyertholen and Fogler. This is consistent with the variational principle that applies to their results.…”

Section: Biexciton Binding Energiesmentioning

confidence: 99%

Exciton-exciton interaction and biexciton formation in bilayer systems

2009

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We report quantum Monte Carlo calculations of biexciton binding energies in ideal two-dimensional bilayer systems with isotropic electron and hole masses. We have also calculated exciton-exciton interaction potentials, and pair distribution functions for electrons and holes in bound biexcitons. Comparing our data with results obtained in a recent study using a model exciton-exciton potential [C. Schindler and R. Zimmermann, Phys. Rev. B \textbf{78}, 045313 (2008)], we find a somewhat larger range of layer separations at which biexcitons are stable. We find that individual excitons retain their identity in bound biexcitons for large layer separations.Comment: 7 pages, 11 figures, 2 table

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“…From these studies one can deduce d c ≈ 7 nm. A straightforward dimensional analysis [18] indicates that d c should scale as the effective electron Bohr radius a e = 2 κ/m e e 2 when changing the compound. Clearly, these arguments can be adopted to a wide single QW as well.…”

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confidence: 99%

“…Full evolution of the shape of the exciton interaction potential as a function of d has been calculated numerically for GaAs coupled quantum wells (CQW's) [17,18]. The structure consists of two GaAs layers separated by a thin AlGaAs barrier [ Fig.…”

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Resonant pairing of excitons in semiconductor heterostructures

Андреев

2016

Phys. Rev. B

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We suggest indirect excitons in 2D semiconductor heterostructures as a platform for realization of a bosonic analog of the Bardeen-Cooper-Schrieffer superconductor. The quantum phase transition to a biexcitonic gapped state can be controlled in situ by tuning the electric field applied to the structure in the growth direction. The proposed playground should allow one to go to strongly correlated and high-temperature regimes, unattainable with Feshbach resonant atomic gases.PACS numbers: 71.35. Lk, 34.50.Cx, 67.10.Ba, 74.10.+v The phenomenon of resonant pairing lies at the heart of superconductivity in metals. Here Cooper pairs of fermionic particles -electrons, can Bose-Einstein condense to carry electric charge without dissipation. In-depth study of this scenario, commonly known as Bardeen-CooperSchrieffer (BCS) theory, has been performed by using the technique of Feshbach resonances (FR's) in ultracold atomic gases. In Fermi gases this technique has allowed for observation of a crossover from a BCS-like state made of spatially overlapping pairs of atoms to a BoseEinstein condensate (BEC) of tightly bound diatomic molecules [1][2][3][4][5]. This so-called BCS-BEC crossover has become a paradigm of the many-body physics, sharing important analogies with high-temperature superconductivity [6] and neutron stars [7][8][9].A natural idea expounded in a series of papers [10] has been to apply the same FR technique to degenerate Bose gases. It has been shown that in the case of bosons the smooth crossover is replaced by a thermodynamically sharp phase transition from a coherent mixture of atoms and molecules to a pure molecular superfluid [11]. The latter is distinguished by the absence of atomic offdiagonal long-range order and gapped atomic excitations. Though being of great fundamental interest on its own right, until now this research has not met its applicationoriented counterpart in the physics of solid state. Moreover, experimental attempts to realize a unitary Bose gas of atoms did not succeed. This is due to coalescence of three and more atoms (few-body recombination) [12,13] and mechanical instability when approaching the resonance on the attractive side [14].In this Letter we propose a new setting for study and manipulation of resonantly paired bosonic superfluids. Bosonic quasiparticles we consider are indirect excitons in biased semiconductor heterostructures. Our excitonic analog of BCS is expected to be stable across the whole range of scattering lengths. The scattering length of the excitons can be conveniently tuned by the bias electric field. A distinct feature of an indirect exciton is a large dipole moment oriented perpendicularly to the structure plane. In the system under consideration an interplay between the long-range dipolar repulsion and the resonant interaction may result in formation of a fragmented biexcitonic supersolid. This new strongly correlated state of bosonic matter would be robust to fluctuations of all kind which usually spoil superconductivity in low dimensions. In transitio...

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Biexcitons in two-dimensional systems with spatially separated electrons and holes

Cited by 44 publications

References 51 publications

High-temperature superfluidity with indirect excitons in van der Waals heterostructures

High-temperature superfluidity with indirect excitons in van der Waals heterostructures

Exciton-exciton interaction and biexciton formation in bilayer systems

Resonant pairing of excitons in semiconductor heterostructures

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