Unusual ground-state properties ofUPd2Al3: Implications for the coexistence of heavy-fermion superconductivity and local-moment antiferromagnetism

We report measurements of the resistivity and the specific heat, performed as a function of temperature, magnetic field, and hydrostatic pressure on the antiferromagnetic (${\mathit{T}}_{\mathit{N}}$=14 K) heavy-fermion superconductor (${\mathit{T}}_{\mathit{c}}$=2 K) ${\mathrm{UPd}}_2$ ${\mathrm{Al}}_3$. Our results suggest a coexistence of two subsystems with more localized 5f states responsible for the magnetic properties and less localized states responsible for the superconducting properties. The latter are compatible with an order parameter of octagonal d-wave symmetry.