Magneto-transport properties of noble metals containing rare-earth impurities

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Abstract
Magneto-transport measurements of noble metals containing rare-earth impurities probe different aspects of the 4f-conduction electron interaction. The anisotropy of the magnetoresistance is primarily due to the quadrupolar term, the extraordinary Hall effect (skew scattering) is at least partially due to the orbital exchange term (l⋅L) and the negative isotropic magnetoresistance is due to the spin exchange term (s⋅S). The advantage of magneto-transport experiments over others, e.g., EPR g-shift and linewidth, is that they single out different terms in the 4f-conduction electron interaction. Estimates of the anisotropic terms based on conduction electrons in plane wave states give values too small to explain the experimental data. We have taken into account the admixture of 5d screening electrons into the conduction band and obtain a 4f-conduction electron interaction which has large anisotropic terms in addition to the conventional spin interaction. When we assume that the 5d electrons are in t2g states we find that our estimate of the anisotropy of the magnetoresistance and of the skew scattering effect are in fair agreement with the experimental data. However, our estimate of the negative isotropic magnetoresistance is too large.