Electrical resistivity, thermopower and thermal conductivity studies of (Sm1-xYx)Cu2 and RCu2 (R identical to Gd, Pr or Tb) systems

Abstract

The authors report the electrical resistivity rho , thermopower S and thermal conductivity lambda studies of (Sm1-xYx)Cu2 and RCu2 (R identical to Gd, Pr or Tb) systems between 4.2 and 300 K. The value of the antiferromagnetic ordering temperature TN for the ((Sm1-xYx)Cu2 systems is found to become depressed, almost linearly, with Y substitution. The value of TN extrapolates to zero as x to 1. Such a behaviour is attributed solely to the dilution effects of Sm by Y atoms. Chemical pressure effects on the value of TN due to addition of Y atoms are found to be negligible. The lambda curves of SmCu2, GdCu2 and TbCu2 exhibit a peak for T < TN. This low-temperature peak at Tmaxlambda approximately= 10 K, in the lambda data of these compounds arises from the combined influence of the electronic and the magnetic contribution to the total lambda . This low-temperature peak becomes suppressed for x >or= 0.10. The S curves exhibit several extremum features, at T <or= TN, which is ascribed to the variation in the density of states at the Fermi level.