Double anomaly in the specific heat of superconducting UPt3 and UPt3B0.11

Stacking faults in UPt3

“…The heavy-fermion superconductor UPt 3 has attracted much experimental and theoretical interest, due to the multiple superconducting phases observed as functions of magnetic field and temperature [1]. The details of the superconducting phase diagram are sampledependent [2], and are strongly affected by compositional modifications [3,4], departures from stoichiometry [5], and by the application of both uniaxial [6] and hydrostatic pressures [7]. In addition, high-temperature annealing is required to obtain the sharpest superconducting transitions and highest transition temperatures.…”

γ-U phase in U-Pt system retained to low temperatures by means of rapid cooling

“…[17,18]. The heavy-fermion superconductor UPt 3 is of a particular interest, since it belongs to the most exotic U-compounds due to its unconventional superconductivity coexisting with pronounced spin fluctuations at low temperatures, revealing a double stepstructure at the superconducting transition at T c = 0.54 K [19] and at about 50 mK below T c [20] and a complex phase diagram with three different superconducting phases as a function of temperature and magnetic field [21]. The weak antiferromagnetic order below T N = 5 K with an extremely small uranium moment of only 0.02µ B /U atom is believed to play a crucial role in the existence of multiple superconducting phases [22,23].…”