Piezoresistivity and conductance anisotropy of tunneling-percolating systems

TL;DR

This paper investigates the piezoresistive response and conductance anisotropy in tunneling-percolating systems, revealing universal geometric properties near the critical point despite nonuniversal conductivity.

Contribution

It demonstrates that the conductance anisotropy exponent remains universal even when the conductivity is nonuniversal, highlighting a geometric origin of this behavior.

Findings

Logarithmic divergence of piezoresistivity near the critical point.

Universality of the conductance anisotropy exponent $$.

Relevance to materials like carbon-black-polymer composites and RuO2-glass systems.

Abstract

Percolating networks based on interparticle tunneling conduction are shown to yield a logarithmic divergent piezoresistive response close to the critical point as long as the electrical conductivity becomes nonuniversal. At the same time, the piezoresistivity or, equivalently, the conductivity anisotropy exponent $\lambda$ remains universal also when the conductive exponent is not, suggesting a purely geometric origin of $\lambda$. We discuss our results in relation to the nature of transport for a variety of materials such as carbon-black--polymer composites and RuO_2-glass systems which show nonuniversal transport properties and coexistence between tunneling and percolating behaviors.