Pressure and magnetic field effects on electrical resistivity and thermopower of Y1-xTbxCo2 system

The electrical resistivity ρ and thermopower S of the Laves phase Y1-xTbxCo2 alloy system have been measured in magnetic fields up to 10T and under pressures up to 8 GPa in the temperature range from 1.5 to 300 K. The residual resistivity of the alloys peaks at the critical composition xc approx. =0.2 of the onset of 4f-moment long-range magnetic order in the Tb sublattice. In the magnetically ordered region of the phase diagram x>xc, an anomalous large positive magnetoresistivity and a pressure effect on resistivity are observed. The variation of the resistivity with alloy composition, magnetic field, and pressure are attributed to the scattering of conduction electrons due to magnetic static disorder within the partially ordered Co 3d itinerant subsystem. The evolution of the temperature dependence of thermopower with pressure are in agreement with this conduction mechanism (author)