Magnetoresistance coefficient

The problem with Eqs. (5) and (6) is that the terms Sps and SRs introduce four new parameters two magnetoresistance coefficients ( and p), and two magneto-Hall coefficients (/S and Pp). These coefficients are defined by Eqs. (A29) and (A32), respectively, in Appendix A, but unless they are known independently, we cannot uniquely determine n, p, pn, and pp from this analysis. 

Table 7.3 Summaty of electrical transport parameters calculated from the resistivity ( ), Hall coefficient (Rh) and magnetoresistance coefficient (a), for select MAX phases. Unless otherwise noted, = [ip = is assumed. Note that this approach can, and does, result in slightly different values than assuming n—p. The residual resistivity ratio is listed in column 4. 

Fig. 6.44. The temperature dependence of the magnetoresistance coefficient of gadolinium. Open and closed circles denote the results of Hiraoka and Suzuki (1971), and McEwen and Webber (1977), respectively.

A complicated behavior of the magnetoresistance MR was found by Lacerda et al. (1996), Yatskar et al. (1999) and Christianson et al. (2001). Above 5 K, the transverse MR is negative and approximately isotropic, whereas at low T it is strongly anisotropic with respect to the crystal axes and changes its sign below 1 K for H Lc. A strong temperature dependence of the Hall coefficient Rh was reported by Narozhnyi et al. (1999b), which is in contrast with the weakly temperature-dependent Rh observed for several other borocarbides (see Section 3.4.2). 

Figure 7. Electrical conductivity (a), Hall coefficient (R ) and magnetoresistance (Ap/pg) (a) carrier density (n and n for electrons and holes, respectively) and mobility (u, u ) (b). (Reproduced with permission from Ref. 12. Copyright 19 6 American Institute of Physics.)...

Magnetic-field effects in the transport coefficients are of particular interest because of the magnetic character of the f-scattering. Due to the enhanced local susceptibility, the Hall effect and the magnetoresistance can be of anomalous size. Figure 21 shows the Hall coefficient Rn T) of CeCu in comparison with the resistivity p(T) (Milliken et al. 1988). Two main features are intriguing besides the larger size of... 

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