Specific heat ofUPt3in magnetic fields up to 24.5 T

We report the first high-precision specific-heat measurements on the heavy-fermion compound ${\mathrm{UPt}}_3$, over a wide temperature (1.4 K<T<40 K) and field range (B<24.5 T), thus covering the metamagnetic transition at 20 T. The data, taken on a single-crystalline sample, show a pronounced low-temperature maximum in the enhanced ${\gamma }^{\mathrm{*}}$ value at 20 T for a field direction in the hexagonal plane. We also investigate the presence of a ${\mathit{T}}^3$ln(T/${\mathit{T}}^{\mathrm{*}}$) contribution to the specific heat in field.