We have studied the AC response of a hopping model in the variable range hopping regime by dynamical Monte Carlo simulations. We find that the conductivity as function of frequency follows a universal scaling law. We also compare the numerical results to various theoretical predictions. Finally, we study the form of the conducting network as function of frequency.

We discuss memory effects in the conductance of hopping insulators due to slow rearrangements of structural defects leading to the formation of polarons close to the electron hopping states. An abrupt change in the gate voltage and corresponding shift of the chemical potential change the populations of the hopping sites, which then slowly relax due to rearrangements of structural defects reduci...

Metal-sample-metal sandwich configuration has been used to investigate DC conductivity in 4 mum thick Nandi flame [Spathodea campanulata P. Beauv.] seed cuticles. J-V characteristics showed ohmic conduction at low fields and space charge limited current at high fields. Charge mobility in ohmic region was 4.06 x 10(-5) (m(2)V(-1)s(-1)). Temperature-dependent conductivity measurements have been c...

Ion conduction in noncrystals (glasses, polymers, etc) has a number of properties in common. In fact, from a purely phenomenological point of view, these properties are even more widely observed: ion conduction behaves much like electronic conduction in disordered materials (e.g., amorphous semiconductors). These universalities are subject of much current interest, for instance interpreted in t...

The mechanical and the electrical properties of polypyrrole (PPy) fibers and electrochemically deposited PPy films were studied. It was found that the PPy fibers showed a significantly higher strength than the PPy films due to better orientation of the molecular structure. The electrochemically prepared PPy films had a higher electrical conductivity than that of the fibers at high temperature. ...

Electrical conductivity and Seebeck coefficient in regioregular poly(3-hexylthiophene) (RR-P3HT) doped with iodine (I2) have been studied in temperature (T) range from 4.2 K to 300 K and from 77 K to 300 K, respectively. In spite of high doping rate (about 30%), RR-P3HT doped with I2 shows a semiconductive behavior in view of temperature dependence of both electrical conductivity and Seebeck co...

We present a theory of the anomalous Hall effect in ferromagnetic (Ga,Mn)As in the regime when conduction is due to phonon-assisted hopping of holes between localized states in the impurity band. We show that the microscopic origin of the anomalous Hall conductivity in this system can be attributed to a phase that a hole gains when hopping around closed-loop paths in the presence of spin-orbit ...

SrO-borovanadate glasses with the nominal composition (V2O5)z(SrO)0.2(B2O3)0.8−z , 0.4 ≤ z ≤ 0.8 were studied by direct current (DC) electrical conductivity, inductively coupled plasma (ICP) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and X-ray-powder-diffraction (XRD). These glasses were prepared by a normal quench technique and the actual compositions of the glasses were det...

Experimental frequency-dependent conductivity relaxation spectra of a number of molten, glassy, and crystalline ionic conductors that show both the presence of the near constant loss ~NCL! and the cooperative ion hopping contribution are analyzed. On decreasing frequency, the NCL appears first but terminates at some frequency nx1. At still a lower frequency nx2 the cooperative ion hopping dispe...