Photoemission spectra of massless Dirac fermions on the verge of exciton condensation

Rist, Stefan; Varlamov, A. A.; MacDonald, Allan H.; Fazio, Rosario; Polini, Marco

doi:10.1103/physrevb.87.075418

Cited by 13 publications

(17 citation statements)

References 67 publications

(50 reference statements)

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“…Similar results were obtained on the basis of a Kubo-formula approach 57 . Within these frameworks, the enhancement is attributed to e-h pairing fluctuations extending above T c for a phase transition into an exciton condensed phase 1,17,18,57,58 . If this scenario is correct, Fig.…”

Section: Discussionmentioning

confidence: 99%

Anomalous low-temperature Coulomb drag in graphene-GaAs heterostructures

et al. 2014

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Vertical heterostructures combining different layered materials offer novel opportunities for applications and fundamental studies. Here we report a new class of heterostructures comprising a single-layer (or bilayer) graphene in close proximity to a quantum well created in GaAs and supporting a high-mobility two-dimensional electron gas. In our devices, graphene is naturally hole-doped, thereby allowing for the investigation of electron-hole interactions. We focus on the Coulomb drag transport measurements, which are sensitive to many-body effects, and find that the Coulomb drag resistivity significantly increases for temperatures o5-10 K. The low-temperature data follow a logarithmic law, therefore displaying a notable departure from the ordinary quadratic temperature dependence expected in a weakly correlated Fermi-liquid. This anomalous behaviour is consistent with the onset of strong interlayer correlations. Our heterostructures represent a new platform for the creation of coherent circuits and topologically protected quantum bits.

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Section: Discussionmentioning

confidence: 99%

Anomalous low-temperature Coulomb drag in graphene-GaAs heterostructures

et al. 2014

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“…The execution and interpretation of a similar experiment on bilayer graphene without the insulating layer might be a much more complicated issue. Also, angle-resolved photoemission spectroscopy and scanning tunneling microscopy can be used to probe the exciton phase in such bilayer system [41].…”

Section: Exciton Order Parametermentioning

confidence: 99%

AA-stacked bilayer graphene in an applied electric field: Tunable antiferromagnetism and coexisting exciton order parameter

et al. 2014

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We study the electronic properties of AA-stacked bilayer graphene in a transverse electric field. The strong on-site Coulomb repulsion stabilizes the antiferromagnetic order in such a system. The antiferromagnetic order is suppressed by the transverse bias voltage, at least partially. The interplane Coulomb repulsion and nonzero voltage stabilize an exciton order parameter. The exciton order parameter coexists with the antiferromagnetism and can be as large as several tens of meV for realistic values of the bias voltage and interaction constants. The application of a transverse bias voltage can be used to control the transport properties of the bilayer.

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“…In particular, they lead to the logarithmic divergence of a drag resistivity as a function of a temperature 23,24 and a pseudogap formation in the single-particle density of states of electrons and holes. 25 Manifestations of Cooper pair fluctuations in tunneling have not been consider previously. Since tunneling conductivity is colossally enhanced in the paired state, one can anticipate its strong enhancement by Cooper pair fluctuations above critical temperature in analogy with the strong contribution of electron-electron Copper pair fluctuations in a superconductor to its diamagnetic susceptibility and electric conductivity.…”

Section: Introductionmentioning

confidence: 98%

Fluctuational internal Josephson effect in a topological insulator film

Efimkin

Lozovik

2013

Phys. Rev. B

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Tunneling between opposite surfaces of a topological insulator thin film populated by electrons and holes is considered. We predict the considerable enhancement of tunneling conductivity by Cooper electron-hole pair fluctuations that are a precursor of their Cooper pairing. Cooper pair fluctuations lead to the critical behavior of tunneling conductivity in the vicinity of critical temperature with the critical index ν = 2. If the pairing is suppressed by disorder, the behavior of tunneling conductivity in the vicinity of the quantum phase transition is also critical with the index μ = 2. The effect can be interpreted as the fluctuational internal Josephson effect, and it is a general phenomenon for electron-hole bilayers. The peculiarities of the effect in other realizations of an electron-hole bilayer are discussed.

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Photoemission spectra of massless Dirac fermions on the verge of exciton condensation

Cited by 13 publications

References 67 publications

Anomalous low-temperature Coulomb drag in graphene-GaAs heterostructures

Anomalous low-temperature Coulomb drag in graphene-GaAs heterostructures

AA-stacked bilayer graphene in an applied electric field: Tunable antiferromagnetism and coexisting exciton order parameter

Fluctuational internal Josephson effect in a topological insulator film

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