Specific heat has been measured down to 0.053 K on a single crystal of the heavy-fermion antiferromagnet ${\text{U}}_3{\text{Ni}}_5{\text{Al}}_{19}$ that orders at $T_{\text{N}}=23\text{K}$. As has been previously reported, these data can be fitted between 0.4 and 4 K by the spin-fluctuation model of Moriya and Takimoto, which describes the contribution of weakly interacting critical spin fluctuations to the specific heat, $C$, where, as $T\to 0$, $C/T={\gamma }_0-a\surd T$. However, below 0.35 K a noticeable divergence in $C/T\sim \text{log}T$ dependence, consistent with the existence of strongly interacting fluctuations, is observed. This increase in the divergence of $C/T$ at the lowest temperatures—which is contrary to the self-consistent renormalization theory of Moriya and Takimoto, which predicts $\surd T$ dependence for $C/T$ as $T\to 0$ and $\text{log}T$ dependence at higher temperatures—has been measured as a function of magnetic field to further understand its origin. The field data in the low-temperature regime, where $C/T\sim \text{log}T$ exhibit scaling with $\Delta B/T^{1.9}$, further evidence that there exist strongly interacting fluctuations below 0.35 K in ${\text{U}}_3{\text{Ni}}_5{\text{Al}}_{19}$.

• Received 15 April 2008

DOI:https://doi.org/10.1103/PhysRevB.78.153108