Erratum: Magnetoconductance in single-wall carbon nanotubes: Electron-electron interaction and weak localization contributions [Phys. Rev. B<b>76</b>, 235432 (2007)]

Choudhury, Paramita Kar; Jaiswal, Manu; Menon, Reghu

doi:10.1103/physrevb.79.169902

Cited by 6 publications

(13 citation statements)

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“…2,6 Indeed, the characteristic corrections to conductivity obtained for 3D systems within the weak localization theory which takes into account electron-electron interactions are written as:…”

Section: -5mentioning

confidence: 99%

Angular magnetoresistance of stretched carbon nanotube sheets

Cimpoiasu

Sandu

Levin

et al. 2012

Journal of Applied Physics

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We have measured the magnetoresistance of stretched sheets of carbon nanotubes in temperatures ranging from 2 K to 300 K and in magnetic fields up to 9 T, oriented either perpendicular or parallel to the plane of the sheets. The samples have been partially aligned by post-fabrication stretching, such that the direction of stretching was either parallel or perpendicular to the direction of applied electric current. We have observed large differences between the magnetoresistance measured under the two field orientations, most pronounced at the lowest temperatures, highest fields, and for the laterally-aligned sample. Treatment of the sheets with nitric acid affects this anisotropy.We analyzed the results within the theoretical framework of weak and strong localization and concluded that the anisotropy bears the mark of a more unusual phenomenon, possibly magnetically-induced mechanical strain.

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Section: -5mentioning

confidence: 99%

Angular magnetoresistance of stretched carbon nanotube sheets

Cimpoiasu

Sandu

Levin

et al. 2012

Journal of Applied Physics

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“…We therefore report direct observation of the oscillatory impedance in aligned bundles of SWNT using HF excitations by performing detailed measurements of transport properties over a wide range of frequency and temperature. In previous works on high frequency properties of dense DWNTs networks, fabricated by ink-jet printing onto the waveguide, a strong frequency dependence of DWNTs microwave parameters as well as abrupt changes in effective permittivity was observed [12].This property could be used in gas sensor applications. We extend on this work by probing few aligned tubes so as to unearth any unique quantum features regarding this strong frequency dependence.Single walled carbon nanotubes SWNTs were synthesized by laser ablation and purified by chemical means, see ref [13] for further details.…”

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confidence: 74%

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confidence: 94%

Observation of impedance oscillations in single-walled carbon nanotube bundles excited by high-frequency signals

Chimowa¹,

Ncube²,

Bhattacharyya³

2015

EPL

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We report experimental observation of impedance oscillations in single-walled carbon nanotubes measured from 100 MHz to 65 GHz on coplanar wave guides and a power law dependence of the differential conductance with bias voltage. From the crossover of the real and imaginary parts of the complex impedance observed in the range of 10 GHz, we estimate a long lifetime of 15 ps that can support the claim of ballistic transport. By measuring the scattering parameters at high-frequencies of a few aligned single-walled bundles at low temperatures we show that, this observation is strongly influenced by the number of tubes available. __________________________________________________________________________________ a) Author to whom correspondence should be addressed. Electronic mail: Somnath.Bhattacharyya@wits.ac.za 2Over the past few decades there have been both theoretical [1,2] and experimental [3][4][5] efforts to understand one dimensional (1D) transport in DC and high frequency regimes. Calculations based on collective (electron) phenomena have predicted alternative current (AC) response that is chirality dependent in single-walled carbon nanotubes (SWNTs) even in the presence of contact effects and a universal inductive to capacitive transition in the imaginary admittance with increase in contact resistance [6]. On the other hand, a semi-classical model based on a transmission line by Burke et al.has predicted possible Luttinger liquid excitations in metallic CNTs achievable in the gigahertz regime by setting up standing voltage waves in the CNTs [7]. Some experimental RF measurements were done on individual or bundle of SWNTs, double-walled CNT (DWNTs) and multi-walled CNTs (MWNTs) but there has not been experimental evidence of some of the theoretical predictions [8,9]. This motivated us to probe the temperature dependent AC response and extend previous works on CNTs.In the high frequency (HF) regime AC conductance is believed to be equivalent to a transmission line composed of kinetic inductance (L k ) and quantum capacitance (C q ) as additional parameters to the magnetic inductance and electrostatic capacitance [6,8]. If the decay length (of voltage waves) is comparable to the mean free path of the carriers and the intrinsic resistance of material is in the linear response regime, the real and imaginary parts of the impedance will be characterised by an oscillatory behaviour corresponding to resonant peaks of the fundamental waves set by the finite length of the transmission line [6]. Experimentally there were several attempts to collectively excite electrons in CNTs and observe impedance oscillations using high frequency which were unsuccessful due to a couple of reasons such as (i) the weak CNT signal from individual SWNTs making it difficult to resolve from instrument noise or (ii) too many CNTs resulted in average (bulklike) properties instead of the expected quantum effects. It is therefore important that a trade-off point between signal strength and number of CNTs be established without losing the indiv...

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“…In all cases the data can been seen to have a low signal to noise ratio at higher temperatures. This is a common problem when performing magnetoresistance measurements [9] and is compensated for by performing such measurements at high fields and lower temperatures [135]. An improved signal to noise ratio is observed in the samples at lower temperatures.…”

Section: Characteristic Measurementsmentioning

confidence: 99%

The electrical transport properties of nitrogen doped carbon microspheres

Wright

Marsicano

Keartland

et al. 2014

Materials Chemistry and Physics

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A suite of four samples of nitrogen doped carbon microspheres, each with a different level of nitrogen dopant, was synthesised in a horizontal chemical vapour deposition reaction. The samples were characterized using scanning electron microscopy, Raman spectroscopy and electron paramagnetic resonance spectroscopy. Scanning electron microscopy showed that microspheres were produced by the reaction. Raman spectroscopy confirmed the graphitic nature of the samples. Electron paramagnetic resonance spectroscopy determined that nitrogen was present in the graphitic lattice and was used as a non-destructive technique to measure the amount of substitutional nitrogen present in the samples. In order to perform electrical transport measurements an automated magneto-transport measurement station was developed in the laboratory. This transport station was computer controlled and contained all of the necessary hardware and software required to perform magneto-electrical transport measurements. Variable temperature electrical transport measurements were performed on all samples to determine their conductive properties. Resistance measurements showed that two of the samples were semiconductors while the other two samples displayed a transition to metallic behaviour at higher temperatures. This transition can be ascribed to the thermal desorption of nitrogen dopant. Models were fitted to the data and the semiconducting behaviour is best explained by a model of fluctuation induced tunnelling while the metallic behaviour is best explained by a quasi-1 dimensional metallic term based on electron-phonon interactions. The IV characteristics of two of the samples display increasing non-linearity of the current's voltage dependence with decreasing temperature. The other two samples exhibit this behaviour at lower temperatures while higher temperature IV data displays a current saturation with increasing voltage. The same models used to explain the resistance measurements can be used to explain the IV characteristics data extremely well. The magnetoresistance data taken with the direction of current flow orientated both parallel and perpendicular to the field, show a transition from negative to positive magnetoresistance with decreasing temperature. The results of these experiments are inconclusive, as a theoretical model of magnetoresistance in systems that conduct via fluctuation induced tunnelling is not well defined. A comparison between the resistance measurements of all four samples was made to determine the effect of nitrogen doping on the samples' ii Abstract electronic transport properties. The result of this comparison was indeterminate. This was due to samples with identical nitrogen dopant levels displaying vastly different conductive properties and indicates that very strict synthesis conditions need to be adhered to in order to ensure sample quality. Resistance measurements were rerun on the two samples that displayed purely semiconducting behaviour to investigate the possibility of atmospheric doping. It was foun...

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Erratum: Magnetoconductance in single-wall carbon nanotubes: Electron-electron interaction and weak localization contributions [Phys. Rev. B76, 235432 (2007)]

Cited by 6 publications

References 0 publications

Angular magnetoresistance of stretched carbon nanotube sheets

Angular magnetoresistance of stretched carbon nanotube sheets

Observation of impedance oscillations in single-walled carbon nanotube bundles excited by high-frequency signals

The electrical transport properties of nitrogen doped carbon microspheres

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