PdV: A System with a High Spin-Fluctuation or Kondo Temperature?

Publisher Website
Google Scholar
Abstract
The temperature dependence of the incremental resistivity Δρ(T) of five dilute PdV alloys, ranging in concentration from 0.15- to 1.0-at.% V, has been measured from 1.4 to 300 K. Δρ (T=0) increases linearly with V content at a rate of 3.26±0.13 μΩ cm/at.% V. Between 10 and 80 K, Δρ(T) increases rapidly with increasing temperature, in a manner characteristic of Matthiessen's-rule breakdown resulting from phonon and impurity scattering with differing anisotropies. Above 80 K, however, Δρ(T) decreases smoothly with increasing temperature; various attempts have been made to fit this high-temperature variation: (i) In terms of a localized-spin-fluctuation (lsf) model, these data are well fitted by Δρ(T)=C+D ln[(T2+θ2)12], with lsf temperature θ estimated at about 160 K for isolated impurities. D, however, does not scale linearly with the V concentration c, and it is necessary to postulate that interimpurity interactions significantly raise θ for the interaction pair, then D∝c(1−c)n. The observed variation of D can be approximately reproduced for n=150. (ii) These high-temperature data are also equally well fitted by the Appelbaum-Kondo expression: Δρ(T)=E{1−(16cos2δν3cos2δν)[(TTK)ln(TTK)]2}. The scaling parameter E increases linearly with c and the Kondo temperature TK is estimated at about 2300 K. Possible variations in the potential phase shift δν indicate that the amount of s-band screening may increase as c increases. Further experiments are necessary, however, to determine the eventual applicability of either model. Finally, estimates are made of the Matthiessen's-rule deviations Δ(T), which are then fitted within the framework of a "parallel conduction" model, in which 1Δ(T)=1αρh(T)+1βρi(T).