Pressure and Substitution Effects on Transport and Magnetic Properties of Y_1-xR_xCo₂Systems with Static Magnetic Disorder

Abstract

The electrical resistivity and thermopower of light-and heavy-rare-earth-based pseudo-binary Y 1Àx R x Co 2 (R = Nd, Gd, and Tb) alloys are measured at temperatures from 2 to 300 K under pressures up to 3.5 GPa. The resistivity and thermopower of Y 1Àx R x Co 2 show unusual large variations with atomic substitution and pressure in the range of x < x m , where an inhomogeneous magnetization of the Co 3d electron subsystem is observed. These results indicate that the low-temperature transport properties of Y 1Àx Nd x Co 2 , as well as of Y 1Àx R Hx Co 2 (R H = heavy rare earth) alloys, are related to conduction electron scattering due to the static magnetic disorder in the itinerant Co 3d electron subsystem. We found that there is a universal relationship between d ln T C =dP and x=x m in Y 1Àx R x Co 2 alloys, where x m is the boundary composition, which separates the alloy phase diagram into regions with uniform and nonuniform magnetizations of the Co-3d electron subsystem.