Electrical resistivity, thermopower, and thermal conductivity of single grained (Y, Tb, Ho, Er)-Mg-Zn icosahedral quasicrystals

We report on measurements of the temperature dependence of the electrical resistivity ρ, the thermopower S, and the thermal conductivity λ of single grained RE-Mg-Zn (RE=Y, Tb, Ho, Er) icosahedral quasicrystals between 5 and 300 K. The resistivity of all four samples is very weakly temperature dependent with a negative slope dρ/dT. The S/T versus temperature curves exhibit a maximum at temperatures between 12 and 15 K. This feature is observed for all here investigated quasicrystalline materials. The appearance of a maximum in the thermal conductivity of (Y, Ho, Er)-Mg-Zn, and a plateau in that of Tb-Mg-Zn is ascribed to a power-law temperature dependence of the mean free path of delocalized quasilattice excitations at intermediate temperatures. A progressive suppression of the maximum in the thermal conductivity data as the de Gennes factor increases indicates for a coupling of the spin system to the lattice.