Search results for "resistivity"
showing 10 items of 385 documents
Pressure-induced magnetic collapse and metallization of TlFe1.6Se2
2017
The crystal structure, magnetic ordering, and electrical resistivity of $\mathrm{TlF}{\mathrm{e}}_{1.6}\mathrm{S}{\mathrm{e}}_{2}$ were studied at high pressures. Below $\ensuremath{\sim}7\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$, $\mathrm{TlF}{\mathrm{e}}_{1.6}\mathrm{S}{\mathrm{e}}_{2}$ is an antiferromagnetically ordered semiconductor with a $\mathrm{ThC}{\mathrm{r}}_{2}\mathrm{S}{\mathrm{i}}_{2}$-type structure. The insulator-to-metal transformation observed at a pressure of $\ensuremath{\sim}7\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$ is accompanied by a loss of magnetic ordering and an isostructural phase transition. In the pressure range $\ensuremath{\sim}7.5\text{--}11\phantom{\rule{…
The influence of topological phase transition on the superfluid density of overdoped copper oxides
2017
We show that a topological quantum phase transition, generating flat bands and altering Fermi surface topology, is a primary reason for the exotic behavior of the overdoped high-temperature superconductors represented by $\rm La_{2-x}Sr_xCuO_4$, whose superconductivity features differ from what is described by the classical Bardeen-Cooper-Schrieffer theory [J.I. Bo\^zovi\'c, X. He, J. Wu, and A. T. Bollinger, Nature 536, 309 (2016)]. We demonstrate that 1) at temperature $T=0$, the superfluid density $n_s$ turns out to be considerably smaller than the total electron density; 2) the critical temperature $T_c$ is controlled by $n_s$ rather than by doping, and is a linear function of the $n_s$…
Soil ionization in earth electrodes by a finite difference time domain scheme
2004
This paper proposes a finite difference time domain numerical scheme devoted to analyze the transient behavior of earth electrodes during the soil breakdown that can take place when a surge current has to be drained. To this aim, Maxwell's equations together with a space-time variable resistivity function are used. The model has been validated by comparing the computed results with data available in the technical literature. Simulation results related to complex earth electrodes of limited extension are reported. Electrodes of larger extension can be easily simulated but requiring more computational resources.
ac conductivity inLa2CuO4
1992
Measurements of the complex ac conductivity are reported for a single crystal of ${\mathrm{La}}_{2}$${\mathrm{CuO}}_{4}$ for frequencies ${10}^{2}$\ensuremath{\le}\ensuremath{\nu}\ensuremath{\le}${10}^{9}$ Hz and temperatures 25\ensuremath{\le}T\ensuremath{\le}300 K. The conductivity follows a power-law behavior ${\mathrm{\ensuremath{\omega}}}^{\mathit{s}}$ with the frequency exponent s independent of temperature and independent of frequency. However, the hopping transport is strongly anisotropic, with s\ensuremath{\approxeq}0.75 within the ${\mathrm{CuO}}_{2}$ planes and s\ensuremath{\approxeq}0.25 perpendicular to the planes.
ERT and IPT surveys to check the integrity of the geomembrane in the landfill of Bellolampo (Palermo, Italy)
2016
In landfills, changes in resistivity and chargeability can be related to the characteristics of the waste and they can be abrupt and considerable within short distances. These physical properties are function of generation, mobility and degree of saturation of the leachate, gas generation, compaction density and variability. These relationships mean that it can be possible to get an overall image of the quantity and characteristics of the waste from surface electrical measurements over the landfill. In this paper, we present and discuss the results of three electrical tomographies carried out in the landfill site of Bellolampo (Palermo, Italy). The main aim of these surveys was to check the…
Sensitivity Analysis Of Multi-Electrode Arrays For Characterizing The Non-Saturated Zone In Groundwater Vulnerability Assessment
2009
The near-surface environment acts as a filter and buffer for contaminants introduced from the surface by anthropogenic activities. For this reason there is a great need to improve our understanding of the shallow subsurface taking into account the increasing demand for vulnerability maps which illustrates the exposure of aquifers against pollution. These maps are designed to show areas of greatest potential for groundwater contamination on the basis of local subsurface conditions. A shallow, unconfined sand-and-gravel aquifer is highly vulnerable to pollutants because rapid recharge gives little time to contaminants to degrade naturally or be adsorbed before reaching the aquifer. Conversely…
Spatial characterization of leachate plume using electrical resistivity tomography in a landfill composed of old and new cells (Belfort, France)
2016
International audience; Located near Belfort (France), the Etueffont landfill was in operation from 1976 to 2002 for the disposal and storage of domestic waste produced by 47,650 inhabitants. The site is comprised of the original landfill site called the old landfill (OL), in operation from 1976 to 1999, and a newer section known as the new cell (NC) which operated from 1999 to 2002. The objective of this study is to determine, using electrical resistivity tomography (ERT), the extent of the leachate plume from the OL and to monitor the efficiency of the liner of the NC. The entire Etueffont site was crisscrossed with 21 electrical profile lines which were traced in summer between 2009 and …
Lévy walks and scaling in quenched disordered media.
2010
We study L\'evy walks in quenched disordered one-dimensional media, with scatterers spaced according to a long-tailed distribution. By analyzing the scaling relations for the random-walk probability and for the resistivity in the equivalent electric problem, we obtain the asymptotic behavior of the mean square displacement as a function of the exponent characterizing the scatterers distribution. We demonstrate that in quenched media different average procedures can display different asymptotic behavior. In particular, we estimate the moments of the displacement averaged over processes starting from scattering sites, in analogy with recent experiments. Our results are compared with numerical…
On the temperature dependence of the electrical conductivity in hot quenched lattice QCD
2011
Extending our recent work, we report on a calculation of the vector current correlation function for light valence quarks in the deconfined phase of quenched QCD in the temperature range 1.16Tc<T<2.98Tc. After performing a systematic analysis of the in fluence of cut-off effects on light quark meson correlators using clover improved Wilson fermions, we discuss resulting constraints on the electrical conductivity in a quark gluon plasma.
Metals with a Strongly Correlated Electron Liquid
2014
In this chapter, we consider the main properties of strongly correlated Fermi systems, which are formed by the fermion condensate leading to the emergence of flat bands. Namely, we consider the residual entropy \(S_0\) related to the flat bands that leads to the violation of the quasiparticle—hole symmetry. The presence of \(S_0\) has a profound impact on the universality of second order phase transitions. In that case under the application of magnetic field the curve of the second order AF phase transitions passes into a curve of the first order ones at the tricritical point, thus leading to a violation of the critical universality of the fluctuation theory. We demonstrate that a jump in t…