Magnetothermopower of single wall carbon nanotube newtwork

Choi, Eun Sang; Suh, Dongseok; Kim, G.T.; Kim, D.C.; Park, Y.W.; Liu, K.; Duesberg, Georg S.; Roth, S.

doi:10.1016/s0379-6779(98)01076-5

Cited by 17 publications

(6 citation statements)

References 3 publications

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“…Unlike electrical and mechanical properties, which have been studied at a single nanotube level [2], the thermal properties of carbon nanotubes have not been measured at a mesoscopic scale. The specific heat, thermal conductivity and thermoelectric power (TEP) of millimeter-sized mats of carbon nanotubes have been measured by several groups [3][4][5][6][7][8][9][10][11][12][13]. Although these studies have yielded a qualitative understanding of the thermal properties of these materials, there are significant disadvantages to these 'bulk' measurements for understanding intrinsic thermal properties of a single nanotube.…”

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confidence: 99%

Thermal Transport Measurements of Individual Multiwalled Nanotubes

et al. 2001

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The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device. The observed thermal conductivity is more than 3000 W/K m at room temperature, which is two orders of magnitude higher than the estimation from previous experiments that used macroscopic mat samples. The temperature dependence of the thermal conductivity of nanotubes exhibits a peak at 320 K due to the onset of Umklapp phonon scattering. The measured thermoelectric power shows linear temperature dependence with a value of 80 µV/K at room temperature.

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Thermal Transport Measurements of Individual Multiwalled Nanotubes

et al. 2001

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“…number of experimental efforts to measure the TEP of single walled carbon nanotubes (SWNTs) using macroscopic 'mat' samples [4][5][6][7][8][9]. These studies showed interesting thermoelectric phenomena, such as sign change of TEP upon absorption and desorption of gas molecules on the sample [6][7][8].…”

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Modulation of Thermoelectric Power of Individual Carbon Nanotubes

2003

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Thermoelectric power (TEP) of individual single walled carbon nanotubes (SWNTs) has been measured at mesoscopic scales using a microfabricated heater and thermometers. Gate electric field dependent TEP-modulation has been observed. The measured TEP of SWNTs is well correlated to the electrical conductance across the SWNT according to the Mott formula. At low temperatures, strong modulations of TEP were observed in the single electron conduction limit.In addition, semiconducting SWNTs exhibit large values of TEP due to the Schottky barriers at SWNT-metal junctions.PACS numbers: 73.23.-b, 73.22.+f, 65.80.+n

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“…The attenuation of the shoulder in S(T) with the pressure puts forward another explanation for the overall temperature dependence. 8,15 If inelastic scattering of electrons on phonons is of importance, then the thermo-…”

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Pressure dependence of the thermoelectric power of single-walled carbon nanotubes

et al. 2002

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We have measured the thermoelectric power ͑S͒ of high-purity single-walled carbon nanotube mats as a function of temperature at various hydrostatic pressures up to 2.0 GPa. The thermoelectric power is positive, and it increases in a monotonic way with increasing temperature for all pressures. The low-temperature (T Ͻ40 K) linear thermoelectric power is pressure independent and is characteristic for metallic nanotubes. At higher temperatures it is enhanced and though S(T) is linear again above about 100 K it has a nonzero intercept. This enhancement is strongly pressure dependent and is related to the change of the phonon population with hydrostatic pressure.Soon after the discovery of multiwalled carbon nanotubes 1 single-walled carbon nanotubes ͑SWNT͒ were synthesized with catalytic metal particles. 2 SWNT span electronic properties from metals to variable gap semiconductors, depending on the chirality and the diameter of the rolled up graphene sheet. 3 It was immediately realized that metallic tubes represent the ultimate one-dimensional conductor, and they generated considerable interest due to the possible realization of the Luttinger liquid ͑LL͒ behavior in nature. Indeed, conductivity measurements performed on individual nanotubes have shown the canonical power-law behavior of conductance as a function of temperature and voltage. 4 Early thermoelectric power ͑TEP͒ experiments performed on nanotube bundles lead to qualitatively similar results: 5-8 a metallic character due to hole carriers, a knee feature ͑change of slope͒ around 100 K, and preparation dependent magnitude. The observed TEP was associated with intrinsic electronic behavior, and the fact that the nanotube bundles contain both metallic and semiconducting ropes allowed a description of the unusual shape of the S(T) curves in a simple two-band model, using a sufficient number of fitting parameters. It was also realized that in the high-temperature range the thermoelectric power is significantly larger than expected for bundles constituted predominantly of metallic ropes. 5 Since SWNT's may be contaminated by magnetic impurities coming from the catalysts ͑Fe, Ni, Co͒ needed for their growth, the high value of the TEP above 100 K questions its intrinsic origin. The influence of the magnetic impurities has clearly been experimentally demonstrated: 9 in the presence of transition-metal impurities the thermopower has a strong peak, just around 100 K. This peak was associated with the Kondo scattering of conduction electrons on the impurity spins. The enhancement of the TEP could be largely, albeit not completely, removed by iodine neutralization. 9 A nonintrinsic, residual ''Kondo term'' may arise from magnetic impurities trapped on the body of the nanotubes, even in the case of nominally pure samples.The change of sign of the thermoelectric power upon degassing also raised the possibility of a nonintrinsic process. 10 The conductivity of doped semiconducting tubes can be as high as that of the metallic ones and the overall thermopower may be determin...

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Magnetothermopower of single wall carbon nanotube newtwork

Cited by 17 publications

References 3 publications

Thermal Transport Measurements of Individual Multiwalled Nanotubes

Thermal Transport Measurements of Individual Multiwalled Nanotubes

Modulation of Thermoelectric Power of Individual Carbon Nanotubes

Pressure dependence of the thermoelectric power of single-walled carbon nanotubes

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