It is argued that in the limit of extreme disorder AC hopping is dominated by ”percolation paths”. Modelling a percolation path as a one-dimensional path with a sharp jump rate cut-off leads to an expression for the universal AC conductivity, that fits computer simulations in two and three dimensions better than the effective medium approximation. 72.20.-i; 72.80.Ng; 66.30.Dn Typeset using REVT...

Electrowetting generates flow patterns inside drops when AC voltages are employed. For AC frequencies around the drop eigenfrequency (typically O(1kHz) or less), capillary waves emanate from the contact line giving rise to a net motion in the bulk of the drop. This flow can be described by a capillary wave-driven Stokes drift. At higher AC frequencies (above 10kHz, depending on liquid conductiv...

The transmission electron microscopy images of in situ prepared multiwall carbon nanotubes MWNTs and polyaniline PANI composites show that nanotubes are well dispersed in aqueous medium, and the nanofibers of PANI facilitate intertube transport. Although low temperature transport indicates variable range hopping VRH mechanism, the dc and ac conductivity become temperature independent as the MWN...

We study the ac-conductivity in linear response theory in the general framework of ergodic magnetic Schrödinger operators. For the Anderson model, if the Fermi energy lies in the localization regime, we prove that the ac-conductivity is bounded by Cν(log 1 ν ) at small frequencies ν. This is to be compared to Mott’s formula, which predicts the leading term to be Cν(log 1 ν ).

We have investigated the conductivity of surface state electrons on liquid 4He films supported by a quench-condensed thin solid hydrogen substrate. A pronounced dip in the ac-conductivity was observed as the He film thickness reached about 10 layers. This phenomenon was studied at different temperatures (range between 1.6 and 210, electron densities from 0.9 to 19x10S cm -2, frequencies between...

The dc and ac conductivities of Mn-doped ZnO were investigated at temperatures from 10 to 100 K. The temperature dependence of the dc conductivity from 10 to 100 K shows an abrupt change at ;18 K, manifesting a much lower activation energy for conduction below 18 K. From 10 to 18 K, the ac conductivity, sac(v), varies as sac(v)5Av s in the frequency range from 10 to 10 Hz with s in the range of...