Resistivity, ρ (T), of LaMnO3+δ displays between δ = 0 − 0.154 an activated behavior both above and below the paramagnetic (PM) to ferromagnetic transition temperature, TC. The relative magnetoresistance at 8 T reaches the values of – 88 % near TC and – 98 % at T ≈ 20 K. In the PM phase ρ (T) satisfies between TC ~130 − 160 K and Tv ∼ 250 − 270 K the Shklovskii – Efros-like variable-range hoppi...

Temperature, T, dependence of the electrical conductivity, σ, of own-made polyaniline pellets, highly doped either by HCl or by dodecylbenzenesulphonic acid, is discussed. For the both dopants, a variable-range-hopping exponent 2/5 is found below T * ≈ 200−250 K. This result can be understood on the basis of a recent theory of Fogler, Teber and Shklovskii which takes into account Coulomb correl...

The physics of ac hopping conduc2ivity in disordered solids is discussed in the light of a recently proposed model. Several new comments are made. One of the most interesting facts about conductivity in disordered solids is the surprising similarity between ionic and electronic conductivity. The same kinds of non-linearities in strong electric fields are observed, and ionic and electronic condu...

Transition-metal chalcogenides are prospective thermoelectric materials. One of them is a molybdenum disulfide MoS2, which has a layered structure. MoS2 has a good potential to have a high value of thermoelectric quality factor due to a high value of thermo-EMF and low value of thermal conductivity. But a low value of its electrical conductivity suppresses the thermoelectric quality factor ZT o...

Numerical calculations of anisotropic hopping transport based on the resistor network model are presented. Conductivity is shown to follow the stretched exponential dependence on temperature with exponents increasing from 14 to 1 as the wave functions become anisotropic and their localization length in the direction of charge transport decreases. For sufficiently strong anisotropy, this results...

Conduction and dielectric behavior of Sr0.97(Ti12xFex)O32d solid solutions were studied. The temperature dependence of the dc conductivity with s}A exp(2BT) obtained, indicated a variable-range hopping mechanism. A low-frequency dielectric relaxation was also observed. The activation energy for the variablerange hopping conduction is slightly higher than that for dielectric relaxation, suggesti...

The temperature and electrical field dependent conductivity of n-type CdSe nanocrystal thin films is investigated. In the low electrical field regime, the conductivity follows sigma approximately exp([-(T(*)/T)(1/2)] in the temperature range 10<T<120 K. At high electrical field, the conductivity is strongly field dependent. At 4 K, the conductance increases by 8 orders of magnitude over one dec...

Froln broad-band temperature dependent transport studies on PAni-blends we can now conclude that the electric conductivity of PAni is governed by charge hopping on aInesoscopic scale between metallic crystalline regions (8 nm) separated by thin amorphous

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...