Excitonic condensation in spatially separated one-dimensional systems

Abergel, David

doi:10.1063/1.4921792

Cited by 13 publications

(13 citation statements)

References 45 publications

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“…Recently ref. 24 discussed a quasi-condensate of excitons in coupled electron-hole one-dimensional wires using the weak-coupled BCS gap equation in the low density limit with only the lowest subband contributing to the pairing, and with screening neglected. Since only one channel was considered, there are no shape resonance effects.…”

Section: Methodsmentioning

confidence: 99%

“…Interestingly, ref. 24 argues that even in the one-channel case, the finite size of the nanoribbons would allow for short range superfluid correlations. In our case the many available channels due to the multiple subbands involved in the pairing allow for a suppression of the critical fluctuations, which would favour the observation of conventional long-range superfluidity.…”

Section: Methodsmentioning

confidence: 99%

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Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons

Zarenia

Perali

Peeters

et al. 2016

Sci Rep

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We predict enhanced electron-hole superfluidity in two coupled electron-hole armchair-edge terminated graphene nanoribbons separated by a thin insulating barrier. In contrast to graphene monolayers, the multiple subbands of the nanoribbons are parabolic at low energy with a gap between the conduction and valence bands, and with lifted valley degeneracy. These properties make screening of the electron-hole interaction much weaker than for coupled electron-hole monolayers, thus boosting the pairing strength and enhancing the superfluid properties. The pairing strength is further boosted by the quasi one-dimensional quantum confinement of the carriers, as well as by the large density of states near the bottom of each subband. The latter magnifies superfluid shape resonances caused by the quantum confinement. Several superfluid partial condensates are present for finite-width nanoribbons with multiple subbands. We find that superfluidity is predominately in the strongly-coupled BEC and BCS-BEC crossover regimes, with large superfluid gaps up to 100 meV and beyond. When the gaps exceed the subband spacing, there is significant mixing of the subbands, a rounding of the shape resonances, and a resulting reduction in the one-dimensional nature of the system.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons

Zarenia

Perali

Peeters

et al. 2016

Sci Rep

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“…The results presented in this work could also be used to consider building up topologically nontrivial 1D excitonic condensates. Recent theory has shown that a core-shell nanowire with band inversion is an interesting platform for the experimental realization of excitonic condensation27.…”

Section: Discussionmentioning

confidence: 99%

Band-inverted gaps in InAs/GaSb and GaSb/InAs core-shell nanowires

Luo

Huang

Liao

et al. 2016

Sci Rep

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The [111]-oriented InAs/GaSb and GaSb/InAs core-shell nanowires have been studied by the 8 × 8 Luttinger-Kohn Hamiltonian to search for non-vanishing fundamental gaps between inverted electron and hole bands. We focus on the variations of the band-inverted fundamental gap, the hybridization gap, and the effective gap with the core radius and shell thickness of the nanowires. The evolutions of all the energy gaps with the structural parameters are shown to be dominantly governed by the effect of quantum confinement. With a fixed core radius, a band-inverted fundamental gap exists only at intermediate shell thicknesses. The maximum band-inverted gap found is ~4.4 meV for GaSb/InAs and ~3.5 meV for InAs/GaSb core-shell nanowires, and for the GaSb/InAs core-shell nanowires the gap persists over a wider range of geometrical parameters. The intrinsic reason for these differences between the two types of nanowires is that in the shell the electron-like states of InAs is more delocalized than the hole-like state of GaSb, while in the core the hole-like state of GaSb is more delocalized than the electron-like state of InAs, and both favor a stronger electron-hole hybridization.

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“…At present, the multi-layer samples are of higher quality than the corresponding single-layer ones, and it is therefore essential that theoretical investigation tackle those more complex, multi-flavor systems. Furthermore, the same method can be used to study lower-dimensional excitonic bound states, which have been recently proposed in two parallel nanowires [55]. This problem will be analyzed in future work.…”

Section: Discussionmentioning

confidence: 99%

Excitonic gap generation in thin-film topological insulators

Menezes

Smith²,

Palumbo³

2017

J. Phys.: Condens. Matter

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In this work, we analyze the excitonic gap generation in the strong-coupling regime of thin films of three-dimensional time-reversal-invariant topological insulators. We start by writing down the effective gauge theory in 2+1-dimensions from the projection of the 3+1-dimensional quantum electrodynamics. Within this method, we obtain a short-range interaction, which has the form of a Thirring-like term, and a long-range one. The interaction between the two surface states of the material induces an excitonic gap. By using the large-N approximation in the strong-coupling limit, we find that there is a dynamical mass generation for the excitonic states that preserves time-reversal symmetry and is related to the dynamical chiral-symmetry breaking of our model. This symmetry breaking occurs only for values of the fermion-flavor number smaller than Nc ≈ 11.8. Our results show that the inclusion of the full dynamical interaction strongly modifies the critical number of flavors for the occurrence of exciton condensation, and therefore, cannot be neglected.

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Excitonic condensation in spatially separated one-dimensional systems

Cited by 13 publications

References 45 publications

Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons

Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons

Band-inverted gaps in InAs/GaSb and GaSb/InAs core-shell nanowires

Excitonic gap generation in thin-film topological insulators

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