Two-magnetization Nordheim model of randomly distributed Co local sites for the anomalous residual resistivity at the magnetic phase boundary of Y1-xRxCo2 system (R: rare earth)

Abstract

The electrical resistivity ν of the Laves phase Y1-xRxCo2 compound system has been measured in magnetic fields up to 10 T and under pressures up to 8 GPa at temperatures from 1.5 to 300 K. The anomalous behavior of residual resistivity has been observed in a region x < xa, where x a is a critical concentration between inhomogeneously and homogeneously ordered phases, and which has a maximum at xc where Tc ≈ 0 with a mean field acting on Co sub-lattice is equal to the itinerant Co metamagnetic critical field Bc. In xc < x < xa, the magneto-resistivity and pressure resistivity are anomalously large with positive sign. However, in the paramagnetic region for x < xc, they are anomalously large but with negative sign.The anomalous behavior is attributed to the s-d scattering of conduction electrons due to statistically disordered Co magnetization. Those phenomena can be explained by a new scattering model of [Two magnetization Nordheim model for randomly distributed Co sites] introduced by us.