Anomalous Fermi Liquid Behavior of the Dilute Uranium Alloys La1-xUxRu2Si2(x≤0.07)

Low temperature properties of the dilute uranium alloys La 1- x U x Ru 2 Si 2 ( x ≤0.07) have been investigated by means of magnetic susceptibility χ, magnetization m , specific heat C P and electrical resistivity ρ measurements to clarify the single-U-site effects of URu 2 Si 2 . Local 5f electrons show a strong magnetic anisotropy along the tetragonal c axis, as is observed in other dilute alloys Th 1- x U x Ru 2 Si 2 and Y 1- x U x Ru 2 Si 2 . As temperature is lowered below ∼60 K, the c -axis susceptibility χ c follows a ln T function, and ρ decreases in proportion to χ c . The 5f electronic specific heat C P 5f / T exhibits a broad peak at ∼10 K. The entropy change associated with this anomaly below 30 K is estimated to be only about 0.3 R ln 2. Although the local Fermi liquid behavior is observed in χ, C P and ρ at very low temperatures, the ln T decrease in ρ and the small entropy change provide a remarkable contrast with those expected in the usual magnetic dilute alloys.