Magnetic and Superconducting Properties of the Heavy-Fermion Superconductor UPd₂Al₃

Zero- and transverse-field muon-spin rotation (mu+ SR) spectroscopy, as well as critical-field investigations were performed on the newly discovered antiferromagnetic superconductor UPd2Al3. In contrast to the situation in UNi2Al3, no spontaneous frequency could be observed in the zero-field spectroscopy, suggesting a symmetric muon stopping site. The coexistence between magnetism and superconductivity could unambiguously be confirmed by the mu+ SR data. The magnetic-penetration depth lambda(0) has been obtained from the increase of the mu+ SR line width below T(c) and from the slopes of the critical field at T(c). The results are compatible with a value of lambda(0) = (6250 +/- 1250) A and suggest that UPd2Al3 is a BCS-type weak-coupling superconductor