Giant modulation of the electronic band gap of carbon nanotubes by dielectric screening

Aspitarte, Lee; McCulley, Daniel R.; Bertoni, Alberto; Island, Joshua O.; Ostermann, Marvin; Rontani, Massimo; Steele, Gary A.; Minot, Ethan D.

doi:10.1038/s41598-017-09372-1

Cited by 19 publications

(21 citation statements)

References 39 publications

(63 reference statements)

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“…A previous study of suspended m-CNTs in dielectric liquids showed that the gap is modulated by dielectric environment. 22 As noted in a number of previous experimental studies, m-CNTs with gaps of order 100 meV cannot be explained by non-interacting-electron band theory. 10,22,34,35 Non-interacting theories predict that m-CNTs have a small band gap due to curvature, axial strain, or twist.…”

Section: Discussionmentioning

confidence: 91%

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Universal interaction-driven gap in metallic carbon nanotubes

et al. 2018

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Suspended metallic carbon nanotubes (m-CNTs) exhibit a remarkably large transport gap that can exceed 100 meV. Both experiment and theory suggest that strong electron-electron interactions play a crucial role in generating this electronic structure. To further understand this strongly-interacting system, we have performed electronic measurements of suspended m-CNTs with known diameter and chiral angle. Spectrally-resolved photocurrent microscopy was used to determine m-CNT structure. The room-temperature electrical characteristics of 18 individualcontacted m-CNTs were compared to their respective diameter and chiral angle. At the charge neutrality point, we observe a peak in m-CNT resistance that scales exponentially with inverse diameter. Using a thermally-activated transport model, we estimate that the transport gap is 450 meV•nm/D where D is CNT diameter. We find no correlation between the gap and the CNT chiral angle. Our results add important new constraints to theories attempting to describe the electronic structure of m-CNTs.

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Section: Discussionmentioning

confidence: 91%

“…Theoretical models describing the transport gap of m-CNTs include enhancement of a bare band gap, 22 the opening of a Mott gap, 7,9,[11][12][13][14] and the opening of an excitonic insulator gap. 17 These theories make a variety of predictions regarding the diameter and chiral angle dependence of the gap.…”

Section: Introductionmentioning

confidence: 99%

Universal interaction-driven gap in metallic carbon nanotubes

et al. 2018

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“…Note that the fabrication for device D was slightly different and follows the method presented in Ref. 20. The magnitude for both devices decreases monotonically with filling.…”

Section: Measurement Summary For Devices B C and Dmentioning

confidence: 99%

“…Theory says that metallic nanotubes can develop a band gap due to symmetry breaking of the underlying graphene lattice from strains, twists and curvature. The magnitude of this gap is predicted to be around tens of milli-electron volts but zero field gaps of an order of a magnitude larger have been reported [19][20][21]. Perhaps most intriguingly though, in the single particle picture, these gaps should vanish at the Dirac field as the nanotube quantization line is pushed to the Dirac point of the underlying graphene band structure resulting in a truly metallic nanotube.…”

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confidence: 97%

Interaction-Driven Giant Orbital Magnetic Moments in Carbon Nanotubes

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Carbon nanotubes continue to be model systems for studies of confinement and interactions. This is particularly true in the case of so-called "ultra-clean" carbon nanotube devices offering the study of quantum dots with extremely low disorder. The quality of such systems, however, has increasingly revealed glaring discrepancies between experiment and theory. Here we address the outstanding anomaly of exceptionally large orbital magnetic moments in carbon nanotube quantum dots. We perform low temperature magneto-transport measurements of the orbital magnetic moment and find it is up to seven times larger than expected from the conventional semiclassical model. Moreover, the magnitude of the magnetic moment monotonically drops with the addition of each electron to the quantum dot directly contradicting the widely accepted shell filling picture of single-particle levels. We carry out quasiparticle calculations, both from first principles and within the effectivemass approximation, and find the giant magnetic moments can only be captured by considering a self-energy correction to the electronic band structure due to electron-electron interactions.arXiv:1809.08347v1 [cond-mat.mes-hall]

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“…Recent experiments suggested signatures of the EI phase in TiSe 2 in the 1T phase . Also, metallic carbon nanotubes can be seen as SMs, thus are candidates to host an EI phase . There are also investigations of Ta 2 NiSe 5 as a host material for the EI phase .…”

Section: Introductionmentioning

confidence: 99%

Quantum Transport Properties of an Exciton Insulator/Superconductor Hybrid Junction

2018

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A theoretical study of electronic transport in a hybrid junction consisting of an excitonic insulator sandwiched between a normal and a superconducting electrode is presented. The normal region is described as a two‐band semi‐metal and the superconducting lead as a two‐band superconductor. In the excitonic insulator region, the coupling between carriers in the two bands leads to an excitonic condensate and a gap Γ in the quasi‐particle spectrum. Four different scattering processes at both interfaces are identified: Two types of normal reflection, intra‐ and inter‐band; and two different Andreev reflections, one retro‐reflective within the same band and one specular reflective between the two bands. The differential conductance of the structure is calculated and the existence of a minimum at voltages of the order of the excitonic gap is shown. The findings are useful toward the detection of the excitonic condensate and provide a plausible explanation for recent transport experiments on HgTe quantum wells and InAs/GaSb bilayer systems.

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Giant modulation of the electronic band gap of carbon nanotubes by dielectric screening

Cited by 19 publications

References 39 publications

Universal interaction-driven gap in metallic carbon nanotubes

Universal interaction-driven gap in metallic carbon nanotubes

Interaction-Driven Giant Orbital Magnetic Moments in Carbon Nanotubes

Quantum Transport Properties of an Exciton Insulator/Superconductor Hybrid Junction

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