Recent theoretical works make clear predictions for the low-temperature properties of non-Fermi-liquid (NFL) systems. We present specific-heat data for the NFL material ${\mathrm{UCu}}_{3.5}{\mathrm{Pd}}_{1.5}$ down to 0.075 K (a factor of 4 lower in temperature than the previously reported data) which allows a test of the competing theories. The theory of Moriya and Takimoto [J. Phys. Soc. Jpn. 64, 960 (1995)] which predicts $C/T\propto -\ln T$ followed by, at lowest temperatures, $C/T\propto 1-\sqrt{T},$ is consistent with the data. Additional low-temperature specific-heat and ac susceptibility data on ${\mathrm{UCu}}_4\mathrm{Pd}$ and ${\mathrm{UCu}}_{4.2}{\mathrm{Pd}}_{0.8}$ are presented which suggest that the former still exhibits magnetism similar to the latter. Surprisingly, ${\mathrm{UCu}}_{3.5}{\mathrm{Pd}}_{1.5}$ also shows a magnetic transition via ac susceptibility at a sufficiently low temperature (∼0.12 K) that the influence on the specific heat is not entirely clear by the lowest temperature of the measurement. The magnetic behavior, including the frequency dependence of the peak in the ac susceptibility, is in qualitative agreement with Griffiths’ [Phys. Rev. Lett. 23, 17 (1969)] phases idea of Castro Neto et al. [cond-mat/9710123, Phys. Rev. Lett. (to be published)].

• Received 6 July 1998

DOI:https://doi.org/10.1103/PhysRevB.58.R10104