Resistivity and Hall Effect

The above model qualitatively illustrates one of the reasons for an increase in resistance, namely, that pores reduce the volume in which the current can flow. Quantitatively, however, the situation is more complex, because the pores will attain a charge in order to direct the current flow around them. The charge distribution will, in general, depend upon a pore s shape and whether or not it is isolated from other pores (i.e. has neutral material in between). Juretschke et al. [6] have shown that, for cylindrical pores that are parallel to the magnetic field (h direction) and 

Our discussion above has mainly been concerned with steady-state current transport, which is of obvious importance for electronic devices. However, transient effects are also of interest, because the current in such devices is usually modulated, often at very high speeds. The pores in SiC, 

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Combined resistivity and Hall-effect measurements provided the first... 

Special attention is paid to transport properties (resistance and Hall effect) because they are very sensitive to external parameters being the base for working mechanisms in many types of sensors and devices. The magnetic field and temperature dependences of resistance and Hall effect are considered in the framework of the percolation theory. Various types of magnetoresistances such as giant and anisotropic ones as well as their mechanisms are under discussion. 

The devices, based on variation of electronic transport properties (mainly, resistance and Hall effect) under action of an external magnetic field, are very popular now and their production is one of the most successful areas of the modern instrument-making industry. In this area, many types of micro... 

L. J. van der Pauw, "A Method of Measuring Specific Resistivity and Hall Effect of Discs... 

The preparation and electrical properties of magnesium mercury, MgjHgj, have been reported. The intermetallic compound was prepared by heating the elements together above 562 °C, at which temperature the compound melts, in an evacuated silica tube. Electrical resistivity and Hall-effect measurements were made from 2.4 to 297 K. No phase transition was observed over this range. The Hall constant was low and the ideal resistivity (the difference between total and residual resistivity) had the form p a T , where a = 1.9 and 1.0 at 11.50K and... 

The effect of pressure on the magnetism of Eu containing clathrates has been studied by means of electrical resistivity and Hall effect measurements [43, 48]. From pressure-dependent electrical resistivity measurements on type-I Eu2Ba6AlgSi36, Tc was shown to increase from 32.8 K at ambient pressure to 36.5 K at 16 kbar this was interpreted as evidence for local-moment magnetism [43]. In the RKKY picture this behavior suggests that pressure moves the system towards the extremum of the first (ferromagnetic) oscillation of /rkky-... 

A rather special case is Yb in which the resistivity and Hall effect measurements under pressure have been made by several investigators at different temperatures (Bridgman, 1954 Souers and Jura, 1963 Stager and Drickamer, 1963 Jayaraman et al., 1963 Stromberg and Stephens, 1964 Jayaraman, 1964 Me Whan et al., 1969 Holzapfel and Severin, 1971 lida, 1972 Jullien and Jerome, 1971 Katzman and Mydosh, 1972). The resistivity of Yb rises by several orders of magnitude with pressure at low temperatures and then abruptly decreases at about 40 kbar. At room temperature the rise in resistivity is not as spectacular, but it is still quite striking. In fig. 9.8 this behavior is shown (from... 

The anomalous normal state properties first identified in the high-Tc cuprate superconductors include the electrical resistivity and Hall effect. The electrical resistivity Pab T)... 

Uhlir A.J. The potentials of infinite systems of sources and numerical solutions of problems in semiconductor engineering. Bell Syst. Tech. J. 1955 34 105-128 Valdes L.B. Resistivity measurements on germanium for transistors. Proc. IRE 1954 42 420 27 Van der Pauw L.J. A method of measuring specific resistivity and Hall effect of discs of arbitrary shape. Phil. Res. Rep. 1958 13 1-9... 

Song et al. [16] reported results relative to a four-point resistivity measurement on a large bundle of carbon nanotubes (60 um diameter and 350 tm in length between the two potential contacts). They explained their resistivity, magnetoresistance, and Hall effect results in terms of a conductor that could be modeled as a semimetal. Figures 4 (a) and (b) show the magnetic field dependence they observed on the high- and low-temperature MR, respectively. 

The methods by which the phenomenon of interconfiguration fluctuations may be studied are (i) determination of lattice constant, (ii) magnetic susceptibility measurements, (iii) Mossbauer spectroscopy, (iv) measurement of electrical resistivity, (v) Hall effect, (vi) X-ray absorption spectroscopy and (vii) X-ray photoelectron emission spectroscopy. It is useful to note that a suite of techniques must be used to detect ICF phenomenon in a system. Nuclear magnetic resonance is sparingly used because not all the systems exhibiting ICF contain magnetically active nuclei. 

K for a number of samples from each stmcture. Shubnikov-de Haas (SdH) oscillations and Hall effect were measured at 1.4-h1.2 K in magnetic fields up to 6 T in order to determine carrier densities N. No significant difference between the carrier densities of the two mesas in all samples was observed neither at P=0 nor under compression (Fig. la, Fig. 2a). Therefore, the anisotropy of the resistance can be fully ascribed to anisotropy of the corresponding mobilities. The mobilities in [1-... 

The atomic disorder associated with the amorphous state leads to completely different transport properties from those encountered in the crystalline state. Experimental results of the electrical resistivity, the Hall effect, magnetoresistance, thermoelectric power and the occurrence of. superconductivity are discussed in section 8. The main emphasis is placed on the electrical resistivity. The occurrence of negative temperature coefficients of the resistivity is related to models based on the extended Ziman theory. In the low temperature regime the resistivity often shows a In T... 

The rare earth metals display a rich variety of transport phenomena, which we shall discuss in the remaining sections. Transport properties were last reviewed by Legvold (1972), who presented data for the resistivity, thermal conductivity and Seebeck coefficient of almost all the rare earth metals together with Hall effect results for the elements Gd-Er. Since 1972 little attention has been given to the thermal conductivity and Seebeck coefficient and, accordingly, we shall concentrate on the resistivity, magnetoresistivity and Hall effect measurements, with particular attentiM to recent studies. 

Several members of the La Cei- Bi solid solution have been prepared as well (Kasuya et al., 1993). They adopt the rocksalt structure of the end-members, and the cubic cell parameter for La0.2Ce0.sBi (6.520 A, assuming a typographical error in the original article) corresponds to the value interpolated between that for LaBi (6.579 A) and CeBi (6.505 A) (Kasuya et al., 1996). Electrical resistivity, transverse and longitudinal magnetoresistance, and Hall effect measurements have been carried out. 

Figure 4.8 (a) Effect of oxygen partial pressure ratio on conduction type of codoped ZnO films, (b) Hole concentration, resistivity, and Hall mobility as a function of oxygen partial pressure. (After Ref [144].)... 

Chwang R, Smith BJ, Crowell CR (1974) Contact size effects on the van der Pauw method for resistivity and Hall coefficient measurement. Solid State Electron 17 1217-1227... 

It is a white crystalline, brittle metal with a pinkish tinge. It occurs native. Bismuth is the most diamagnetic of all metals, and the thermal conductivity is lower than any metal, except mercury. It has a high electrical resistance, and has the highest Hall effect of any metal (i.e., greatest increase in electrical resistance when placed in a magnetic field). 

The main cause of anode wear is electrochemical oxidation or sulfur attack of anodic surfaces. As copper is not sufficiently resistant to this type of attack, thin caps of oxidation and sulfur-resistant material, such as platinum, are bra2ed to the surface, as shown in Eigure 15a. The thick platinum reinforcement at the upstream corner protects against excessive erosion where Hall effect-induced current concentrations occur, and the interelectrode cap protects the upstream edge from anodic corrosion caused by interelectrode current leakage. The tungsten undedayment protects the copper substrate in case the platinum cladding fails. 

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