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            Magnetic Flux Modulation of the Energy Gap in Nanotube Quantum Dots

Coskun, Ulas; Wei, Tzu-Chieh; Vishveshwara, Smitha; Goldbart, Paul M.; Bezryadin, Alexey

doi:10.1126/science.1096647

Cited by 129 publications

(105 citation statements)

References 24 publications

(47 reference statements)

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“…Since the chirality enters the problem as a fictitious flux, the physical properties of graphene tubes can be dramatically affected by the presence of an axial magnetic field as was anticipated theoretically [7,11,12] and observed experimentally [13]. Indeed, imagine there is an axial Aharonov-Bohm (AB) flux Φ [14] entirely confined within the interior of the cylinder.…”

Section: Effects Of An Axial Magnetic Fieldmentioning

confidence: 92%

“…First we note that there is a series of conductance measurements [13,[15][16][17] and an expertise on how to deal with the end effects is growing. For example, Javey et al [17] found that the resistance of a nanotube was rather close to the expected 6.5 kΩ; they estimated that the leads and contacts contributed no more than 0.6 kΩ (and much less at low temperatures).…”

Section: Effects Of Finite Lengthmentioning

confidence: 99%

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Interplay of Aharonov-Bohm, chirality, and aspect-ratio effects in the axial conductance of a nanotube

2012

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A magnetic field applied along the axis of a nanotube can counteract the effect of the tube chirality and dramatically affect its conductance, leading to a way to determine the chirality of a nanotube. The effect of the applied field is strongest in the long tube limit where the conductance is (i) either a sequence of sharp 4e 2 /h height peaks located at integer values of the flux (for an armchair tube) or (ii) a periodic sequence of pairs of 2e 2 /h height peaks for a chiral tube, with the spacing determined by the chirality. In the short tube limit the conductance takes on the value that gives the universal conductivity of an undoped graphene sheet, with a small amplitude modulation periodic in the flux.PACS numbers: 73.50. Td, 73.23Ad, I. CONDUCTANCE OF GRAPHENE SHEET AND NANOTUBES Katsnelson[1] has given a very general and elegant explanation of the experimental observation that at zero temperature an ideal graphene sheet has conductivity of the order e 2 /h. Although earlier considerations [2] arrived at essentially the same conclusion, Katsnelson's argument stands out because it clearly demonstrates that the finite conductivity of graphene is a direct consequence of the electron dynamics, which is described by the twodimensional massless Dirac equation. Katsnelson [1] has considered an undoped graphene sheet in the shape of a cylinder of length L and circumference W (with both length scales significantly larger than the lattice spacing of graphene) attached at its bases to heavily doped graphene leads and demonstrated by means of the Landauer transmission formula [3] that the axial conductivity of the cylinder in the ring limit, W/L → ∞, approaches the universal 4e 2 /πh value. The crucial element of the analysis is an expression for the transmission probability of propagating modes in the leads [1]

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Section: Effects Of An Axial Magnetic Fieldmentioning

confidence: 92%

Section: Effects Of Finite Lengthmentioning

confidence: 99%

Interplay of Aharonov-Bohm, chirality, and aspect-ratio effects in the axial conductance of a nanotube

2012

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“…[19][20][21][22][23][24][25] Further theoretical studies [26][27][28][29] reveal that the transport properties are directly related to the magnetic-field modulated density of states. The SOI-modified band structure and its implications on the electronic properties of CNT's in a magnetic field have been in the focus of extensive theoretical work.…”

Section: Introductionmentioning

confidence: 99%

Signatures of spin-orbit interaction in transport properties of finite carbon nanotubes in a parallel magnetic field

2011

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The transport properties of finite nanotubes placed in a magnetic field parallel to their axes are investigated. Upon including spin-orbit coupling and curvature effects, two main phenomena are analyzed that crucially depend on the tube's chirality: (i) Finite carbon nanotubes in a parallel magnetic field may present a suppression of current due to the localization at the edges of otherwise conducting states. This phenomenon occurs due to the magnetic-field-dependent open boundary conditions obeyed by the carbon nanotube's wave functions. The transport is fully suppressed above threshold values of the magnetic field, which depend on the nanotube chirality, length, and on the spin-orbit coupling. (ii) Reversible spin-polarized currents can be obtained upon tuning the magnetic field, exploiting the curvature-induced spin-orbit splitting.

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“…On the other hand, in hole-or electron doped nanotubes the behaviour of µ orb (φ) depends strongly on the chirality of the nanotube, on its size, and on the degree of hole or electron doping. In our model calculations we study nanotubes in the ballistic regime and we work in the non-interacting electrons approximation which has yielded good agreement with experimental results in mesoscopic rings [7] and in carbon nanotubes [3,8,9].…”

Section: Introductionmentioning

confidence: 52%

Orbital magnetic moments in pure and doped carbon nanotubes

2005

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The unusual band structure of carbon nanotubes (CNs) results in their remarkable magnetic properties. The application of magnetic field parallel to the tube axis can change the conducting properties of the CN from metallic to semiconducting and vice versa. Apart from that B induces (via the Bohm-Aharonov effect) orbital magnetic moments µ orb in the nanotube. These moments are studied both in pure and hole-or electron-doped CNs, isolated or in a circuit. Remarkably, µ orb in pure CNs depends uniquely on their original conducting properties, length, and temperature but it does not depend on the nanotube radius or the particular chirality. In doped nanotubes the magnetic moments can be strongly altered and depend on the radius and chirality. Temperature can even change their character from diamagnetic at low T to paramagnetic at high T . A full electron-hole symmetry in doped tubes is also revealed.

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h/e Magnetic Flux Modulation of the Energy Gap in Nanotube Quantum Dots

Cited by 129 publications

References 24 publications

Interplay of Aharonov-Bohm, chirality, and aspect-ratio effects in the axial conductance of a nanotube

Interplay of Aharonov-Bohm, chirality, and aspect-ratio effects in the axial conductance of a nanotube

Signatures of spin-orbit interaction in transport properties of finite carbon nanotubes in a parallel magnetic field

Orbital magnetic moments in pure and doped carbon nanotubes

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