Terahertz conductivity peak in composite materials containing carbon nanotubes: Theory and interpretation of experiment

A model for the effective conductivity of a dilute and disordered composite material containing randomly single-wall carbon nanotube (SWCNT) inclusions was formulated. The modification of electron transport by the surface curvature of SWCNTs and an axial depolarization effect due to the finite length of metallic SWCNTs are taken into account. Simultaneous consideration of both effects permits the correct interpretation of the dependences of the effective conductivity on the frequency and temperature, and explains an experimentally observed terahertz peak in the spectrum of the effective conductivity.