%0 Book Section %1 statphys23_0751 %A Johner, N. %A Ryser, P. %A Grimaldi, C. %A Balberg, I. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K d.c. non-universality statphys23 topic-9 transport tunneling-percolation %T D.C. transport criticality of continuum tunneling-percolation systems %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=751 %X The problem of transport non-universality in disordered conductor-insulator composites is still not completely understood. Recently the analysis of a lattice tunneling percolation model and a mean field study of tunneling percolation in the continuum has shed new light on the discrepancies found between the experimentally observed D.C. transport exponents and those predicted by theory. \\In this work we extend this analysis by numerically studying a continuum tunneling-percolation model. We consider a system of identical spherical particles dispersed in a three-dimensional continuum insulating matrix. We determine the percolation critical density for semi-permeable spheres by using a scaling analysis. \\For the study of the conductivity and transport exponent of our system, we use a decimation procedure, allowing us to extract the true critical exponent by making a scaling analysis of the conductivity at the percolation threshold. We find that, independently of the tunneling parameters, the transport exponent is always universal. \Øn the other hand, when the transport exponent is obtained by a fit of the conductivity of the system as a function of the particle density, we obtain a D.C. transport exponent depending on the tunneling parameters and larger than the universal value, showing that apparent non-universality appears. This result shows that the frequently observed non-universality in disordered conductor-insulator composites can be explained without invoking divergent distribution functions of the microscopic conductances.

@incollection{statphys23_0751, abstract = {The problem of transport non-universality in disordered conductor-insulator composites is still not completely understood. Recently the analysis of a lattice tunneling percolation model and a mean field study of tunneling percolation in the continuum has shed new light on the discrepancies found between the experimentally observed D.C. transport exponents and those predicted by theory. \\In this work we extend this analysis by numerically studying a continuum tunneling-percolation model. We consider a system of identical spherical particles dispersed in a three-dimensional continuum insulating matrix. We determine the percolation critical density for semi-permeable spheres by using a scaling analysis. \\For the study of the conductivity and transport exponent of our system, we use a decimation procedure, allowing us to extract the true critical exponent by making a scaling analysis of the conductivity at the percolation threshold. We find that, independently of the tunneling parameters, the transport exponent is always universal. \\On the other hand, when the transport exponent is obtained by a fit of the conductivity of the system as a function of the particle density, we obtain a D.C. transport exponent depending on the tunneling parameters and larger than the universal value, showing that apparent non-universality appears. This result shows that the frequently observed non-universality in disordered conductor-insulator composites can be explained without invoking divergent distribution functions of the microscopic conductances.}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Johner, N. and Ryser, P. and Grimaldi, C. and Balberg, I.}, biburl = {https://www.bibsonomy.org/bibtex/2465b594f8f263ef54d9e7e0863fc603b/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {c06b7affb25f28402c2ba23f2cb9822d}, intrahash = {465b594f8f263ef54d9e7e0863fc603b}, keywords = {d.c. non-universality statphys23 topic-9 transport tunneling-percolation}, month = {9-13 July}, timestamp = {2007-06-20T10:16:28.000+0200}, title = {D.C. transport criticality of continuum tunneling-percolation systems}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=751}, year = 2007 }