Properties of the localized-spin-fluctuating system Pt Co. II. Resistivity and magnetoresistance

The results of measurements of the resistivity and magnetoresistance of a Pt-0.061-at.%-Co sample---the susceptibility and magnetization of which had been the subject of a previous investigation---are reported. These transport measurements were performed between 1.5 and 10 K in applied magnetic fields of 0, 10, 25, and 59 kOe. The zero-field electrical-resistivity data are well fitted by the modified localized-spin-fluctuation (lsf) expression: Δρ(T)=A+B ln[(T²+²)1/2], and the lsf characteristic temperature is estimated at 0.7±{}0.1 K for the dilute Pt Co system. Except at the highest field and lowest temperatures, the remainder of these data are also well fitted by the above expression for the incremental resistivity, with T (in the presence of a magnetic field H) replaced by an effective temperature Teff of the form Teff²=T²+(gμBkB)² H². The actual fitting scheme provides strong supporting evidence for the phenomenologically assumed form of Teff, and yields a g value of 1.5±{}0.1. The validity of the so-called Knapp plots has been investigated, and a generalized form applicable in a magnetic field suggested, Δρ(H, T)∝μeff²(Teff).