Magnetism and superconductivity in UT2Al3 (T=Pd, Ni) and UGe2

We review magnetic and superconducting properties of UT2Al3 (T <f>=</f> Pd, Ni) and UGe2 together with URu2Si2. For UPd2Al3, we have suggested that the superconducting attractive paring interaction is mediated by magnetic excitons. Knight shift measurements of UNi2Al3 show an odd parity pairing in contrast to an even parity formation in UPd2Al3. The ac magnetic susceptibility measurements of UGe2 indicate that the volume fraction of superconductivity grows with increasing pressure, suggesting inhomogeneous coexistence of superconductivity and ferromagnetism. Recent dc magnetization measurements on UGe2 exhibit a step like hysteresis loop at low temperatures. An analysis of the data suggests that a magnetic domain size is smaller than a superconducting coherence length. Finally, we report the observation of an anomaly appearing in the thermal expansion of URu2Si2 under high pressures, which can be ascribed to the phase transition between a hidden and antiferromagnetic order. [Copyright &y& Elsevier]