Kondo effect on Nucler Quadrupole Interaction

PrPt 5是一种超精细增强型核磁体。通过比热测量，在2 mK下观察到了核磁有序。此外，我们观察到一个强烈增强的核四极相互作用约6 mK。由于核四极相互作用很大，我们可以在相当高的温度范围内研究核四极相互作用对电阻的影响。令人惊讶的是，含有Pt杂质相的PrPt 5具有超导电性。然后，我们研究了含Pt杂质相的PrPt 5中核铁磁性和II型超导电性的共存。它在零磁场下表现出超导电性，Ts=213 mK，并且在铁磁核有序温度（Tc = 2 mK）以下，上临界场Hc 2受到显著的抑制（但有限）。由于铁磁有序的存在，低临界场Hc 1（~ 1 mT）被抑制到0.5mT。在大于1 mT的磁场下，直到0.2mK的最低测量温度，自发核磁化与II型超导共存。在零磁场下，我们认为M. L. Kulic，A. I. Buzdin和L. N. Bulaevskii讨论的类畴磁态与Meissner态共存。然而，在单相样品的PrPt 5，超导性没有观察到。我们不知道原因。我们还研究了P波超导体和超精细增强型核磁体PrOs_4Sb_（12）。但在0.2 mK以下没有观察到核磁有序。

PrPt5 is a hyperfine enhanced nuclear magnet. By specific heat measurement, Nuclear magnetic ordering was observed at 2mK. Furthermore, we observed a strongly enhanced nuclear quadrupole interaction of about 6mK. Owing to the large nuclear quadrupole interaction, we can study the effect of nuclear quadrupole interaction on resistance at rather higher temperature range of mK. To our's surprise, PrPt5 with Pt impurity phase became superconductivity. Then, we study on the coexistence of nuclear ferromagnetism and type-II superconductivity in PrPt5 with Pt impurity phase. It exhibits superconductivity at Ts=213 mK in zero field and a remarkable suppression (but finite) of the upper critical field Hc2 below a ferromagnetic nuclear ordering temperature (Tc〜2 mK). The lower critical field Hc1(〜1mT) is suppressed to 0.5mT by the presence the ferromagnetic order. The spontaneous nuclear magnetization coexists with superconductivity of Type II at field lager than 1mT down to the lowest measured temperature of 0.2 mK. At zero field, we think that a Domain-like magnetic state discussed by M.L.Kulic, A.I.Buzdin and L.N.Bulaevskii co-exists with the Meissner state. However, In a single phase sample of PrPt5, a superconductivity was not observed. We do not know the reason. We also study P-wave superconductor and a hyperfine enhanced nuclear magnet PrOs4Sb12. But nuclear magnetic ordering was not observed down to 0.2 mK.