ELECTRICAL-RESISTIVITY, THERMOPOWER AND THERMAL-CONDUCTIVITY STUDIES OF (SM1-XYX)CU2 AND RCU2 (R-EQUIVALENT-TO-GD, PR OR TB) SYSTEMS

We report the electrical resistivity rho, thermopower S and thermal conductivity lambda studies of (Sm1-xYx)Cu2 and RCu2 (R = Gd, Pr or Tb) systems between 4.2 and 300 K. The value of the antiferromagnetic ordering temperature T(N) for the (Sm1-xYx)Cu2 systems is found to become depressed, almost linearly, with Y substitution. The value of T(N) extrapolates to zero as x --> 1. Such a behaviour is attributed solely to the dilution effects of Sm by Y atoms. Chemical pressure effects on the value of T(N) due to addition of Y atoms are found to be negligible. The lambda curves of SmCu2, GdCu2 and TbCu2 exhibit a peak for T < T(N). This low-temperature peak, at T(max)lambda congruent-to 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 greater-than-or-equal-to 0.10. The S curves exhibit several extremum features, at T less-than-or-equal-to T(N), which is ascribed to the variation in the density of states at the Fermi level.