Magnetic and non-Fermi-liquid properties ofU1−xLaxPd2Al3

Abstract

We have performed measurements of the temperature dependence of the electrical resistivity, specific heat, and magnetic susceptibility of polycrystalline samples of ${\mathrm{U}}_{1\ensuremath{-}x}{\mathrm{La}}_{x}{\mathrm{Pd}}_{2}{\mathrm{Al}}_{3}.$ The antiferromagnetic order of the parent compound ${\mathrm{UPd}}_{2}{\mathrm{Al}}_{3}$ is rapidly suppressed for small lanthanum concentrations $0<~x<~0.2.$ For samples with lanthanum concentrations $0.25<~x<~0.65,$ magnetic relaxation and ac magnetic-susceptibility measurements indicate the formation of a spin-glass state with a freezing temperature that extrapolates to $T=0\mathrm{K}$ near $x=0.8.$ Non-Fermi-liquid temperature dependences in the electrical resistivity $\ensuremath{\rho}(T)$ and specific heat $C(T)$ were observed for samples with $x=0.8$ and 0.9. The resistivity $\ensuremath{\rho}(T)$ at low temperatures can be described by a power law $\ensuremath{\rho}/{\ensuremath{\rho}}_{0}=1\ensuremath{-}{\mathrm{AT}}^{n}$ for $T<10\mathrm{K}$ with $n=1.3\ifmmode\pm\else\textpm\fi{}0.1$ for the samples with $x=0.8$ and 0.9. The electronic specific-heat coefficient $\ensuremath{\Delta}C/T$ has a logarithmic temperature dependence in the temperature ranges $3\mathrm{K}<~T<~20\mathrm{K}$ $(x=0.8)$ and $1\mathrm{K}<~T<~6\mathrm{K}$ $(x=0.9).$