Resistivity of some light - heavy rare earth alloys

Abstract

Measurements have been made of the electrical resistivity of four light-heavy rare earth alloy systems, ie-La-Dy, Nd-Dy,Nd-Y,Pr-Tb in the temperature region 2.7-300(400 K).The resistivity variation with temperature in the different crystallographic phases has been explained as follows: 1) in the hop phase - the main contribution comes from spin disorder scattering which may be described theoretically by the RKKY theory. The parameters which are most likely to vary in the series are discussed. 2) in the d-hex phase there are two contributions to the resistivity which are of the same order, ς phon. and ς c.f. These are due to phonon scattering and crystal field scattering. The phonon resistivity ς phon has been approximated to ς La. ς c.f. has been calculated theoretically, for Pr, and Fr-Tb in the d-hex structure and qualitatively discussed for Nd, Nd-Y and Nd-Dy. 3) in the Sm-phase, the resistivity can be discussed in a similar way to the resistivity in the hcp phase or in the d-hex phase, depending on the effective Fermi surface area and the magnetic moment. La and La-Dy alloys in the d-hex phase have been explained in terms of rapid changes of the density of states at the Fermi energy. The residual resistivity in the hep phase has been found to, agree, at low concentrations of the light rare earths, with the previously published results, being dependant of AS(^2)(_eff), suggesting that the magnetic scattering varies as S(S+1) at these concentrations rather then (g-1) (^2) J(J + 1). ς redidual has been found to change only slightly in the Sm phase while in the d-hex structure it shows a normal behaviour for nonmagnetic alloys which order or become superconducting. The variation of the total resistivity with temperature is presented for all the alloys measured on the following four figures 1- 4.