Anisotropy ratio, resistivity

The specific resistance of natural graphite crystals is ca Hem (room temperature) along the a axis parallel to the network basal plane. The resistance along the c axis (perpendicular to the basal plane) is ca 1 Q. The cja axis anisotropy ratio is, therefore, ca 10 . Screw dislocations within the crystal may short-circuit the current path parallel to the c axis and cause lower anisotropic ratios separation of planes may cause higher anisotropic ratios. 

La2.xSrxCuo 98Mno 0204 and of the resistivity anisotropy ratio in Lai 97Sro o3Cu04 obtained in Ref. 4... 

Fig. 74. Anisotropic resistivity in nonstoichiometric rutile Ti02 x, where p and pc are a- and c-axis resistivities, respectively, (a) Anisotropy ratio p /ptf at —60°C vs. pat where p and Rtt decrease with increasing oxygen deficiency X. Rtt(c axis) < Rc(Ti) for pa < approx. 10 ohm-cm. The sharpness of the breakdown in pa with Rtt(a axis) is not apparent from this type of plot, (b) The o-axis and c-axis resistivities vs. temperature for composition G, a nonstoichiometric rutile. (Adaoted from Hollander and Castro (278).)...

The striking different temperature dependencies for the in and out of plane resistances suggest an interpretation in terms of a non-Fermi liquid approach for 7 >r , although p (7) is not far from a conventional behavior. Figure 15 emphasizes the remarkable feature of (TMTSF)2PFj, namely, opposite temperature dependencies for interplane and chain resistivities above T . A temperature independent anisotropy ratio is indeed observed below 10 K in... 

Figure 16 Anisotropy ratio for the resistance along the a and c directions in...

Figure 5.13 Isotropic residual resistivity p (left), and spontaneous magnetoresistance anisotropy ratio A p/p (right) of disordered BCC-Fe Coj alloys calculated in four different...

In contrast to the sp /sp ratio determining the electrical properties, the microstructure of the carbon film plays a vital role in its electrical properties. An anisotropy in resistivity is found with magnetron-sputtered carbon, which shows a diamond and a graphitic phase below and above a deposition temperature of 100°C. These phenomena are considered to be due to peculiarities of the film microstructure [67]. 

Note that AR = 1 for an isotropic crystal. The physical significance of this ratio is that it represents a measure of the relative response of cubic crystals to two different types of shear strain C44 is an indicator of shear resistance in the <100> directions on 100 planes, whereas the quantity (cn — ci2)/2 is an indicator of shear resistance in the <110> directions on 110 planes. Values of anisotropy ratios for various cubic crystals are listed in Table 3.1. Among cubic metals, W is essentially isotropic and A1 is very close to being so. Many materials listed in Table 3.1 have anisotropy ratios which depart significantly from unity. 

The sand-shale sequence containing a thinly laminated section at the depth interval x210-255 can be easily identified by very high anisotropy ratios >8 (Track 1). Track 2 presents the resistivities. In the section, the horizontal resistivity is dominated by the lower resistivity shale. In the laminated interval, the horizontal resistivity shows very modest increase to 1.0-1.3 Q m, while the vertical resistivity is over a decade higher (up to 20 Q m), indicating the presence of hydrocarbon-bearing sand laminations. 

Here p and pj are the transverse and longitudinal resistivities with respect to the magnetization direction, respectively. The off-diagonal element pn represents the spontaneous or anomalous Hall resistivity (AHR) [3]. Conventionally, the anisotropy of the resistivity is expressed by the SMA ratio... 

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