Evidence for superlocalization on a fractal network in conductive carbon-black–polymer composites

Putten, D. van der; Moonen, J. T.; Brom, H.B.; Brokken-Zijp, Jcm José; Michels, M.A.J.

doi:10.1103/physrevlett.69.494

Cited by 137 publications

(62 citation statements)

References 19 publications

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“…δ = 0.75 is higher than the Mott value of δ = 0.25 associated with a flat density of states and the value of δ = 0.5 derived by Efros and Shklovskii [21] for the zero temperature Coulomb gap. However, experiments on materials such as ultrathin metal films find values for δ = 0.75 ± 0.05 [13,14,15,16,17] in agreement with our value of δ for large E g . The mechanism behind this exponent has been a puzzle [13,36].…”

Section: Density Of Statessupporting

confidence: 91%

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1/fnoise in electron glasses

Shtengel

2003

Phys. Rev. B

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We show that 1/ f noise is produced in a 3D electron glass by charge fluctuations due to electrons hopping between isolated sites and a percolating network at low temperatures. The low frequency noise spectrum goes as ω −α with α slightly larger than 1. This result together with the temperature dependence of α and the noise amplitude are in good agreement with the recent experiments. These results hold true both with a flat, noninteracting density of states and with a density of states that includes Coulomb interactions. In the latter case, the density of states has a Coulomb gap that fills in with increasing temperature. For a large Coulomb gap width, this density of states gives a dc conductivity with a hopping exponent of ≈ 0.75 which has been observed in recent experiments. For a small Coulomb gap width, the hopping exponent ≈ 0.5.

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Section: Density Of Statessupporting

confidence: 91%

“…However, for large values of E g , δ ≈ 0.75. Both values have been seen experimentally [11,13,14,15,16,17]. In section III, we present our results.…”

Section: Introductionsupporting

confidence: 67%

1/fnoise in electron glasses

Shtengel

2003

Phys. Rev. B

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“…A similar hopping exponent has been reported by other authors [5,10,13,14], but has rarely been discussed per se. Since there is no theory which predicts this value of the hopping exponent, its origin has been left an open question.…”

Section: Introductionsupporting

confidence: 55%

Anomalous hopping exponents of ultrathin metal films

et al. 2000

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The temperature dependence of the resistance R(T ) of ultrathin quench-condensed films of Ag, Bi, Pb and Pd has been investigated. In the most resistive films films, R(T ) = R0 exp (T0/T ) x , where x = 0.75 ± 0.05. Surprisingly, the exponent x was found to be constant for a wide range of R0 and T0 in all four materials, possibly implying a consistent underlying conduction mechanism. The results are discussed in terms of several different models of hopping conduction.

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“…1 This prediction is confirmed by various granular metals compounds and model systems which have been found to follow Eq. (1) with t ≃ 2.0, [2][3][4][5] that is the value obtained by numerical calculations on three-dimensional random resistor network (RRN) models. 6 In addition to systems showing universality, a large number of disordered compounds displaying values of t larger than t ≃ 2.0 have been repeatedly reported, [7][8][9][10][11][12][13] so that in the present situation it appears that t can assume any value between t ≃ 2.0 up to about t ∼ 6.0 − 7.0.…”

Section: Introductionsupporting

confidence: 54%

Segregated tunneling-percolation model for transport nonuniversality

et al. 2003

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We propose a theory of the origin of transport nonuniversality in disordered insulating-conducting compounds based on the interplay between microstructure and tunneling processes between metallic grains dispersed in the insulating host. We show that if the metallic phase is arranged in quasi-one dimensional chains of conducting grains, then the distribution function of the chain conductivities g has a power-law divergence for g → 0 leading to nonuniversal values of the transport critical exponent t. We evaluate the critical exponent t by Monte Carlo calculations on a cubic lattice and show that our model can describe universal as well nonuniversal behavior of transport depending on the value of few microstructural parameters. Such segregated tunneling-percolation model can describe the microstructure of a quite vast class of materials known as thick-film resistors which display universal or nonuniversal values of t depending on the composition.

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Evidence for superlocalization on a fractal network in conductive carbon-black–polymer composites

Cited by 137 publications

References 19 publications

1/fnoise in electron glasses

1/fnoise in electron glasses

Anomalous hopping exponents of ultrathin metal films

Segregated tunneling-percolation model for transport nonuniversality

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