5-electron states in NpPdAl and the origin of the heavy fermion state

Metoki, Naoto; Aoki, Dai*; Griveau, J.-C.*; Otsuki, Junya*

no journal, , 

Non-Krammers trivalent Np(5) ion in the heavy fermion superconductor NpPdAl shows =4, similar to Pr. We determined the singlet ground state of and the first excited doublet of above 49 K from the quantitative analysis of the magnetic susceptibility and the magnetization curve. The must contribute to the heavy fermion, since the singlet ground state alone cannot, where 2-channel Kondo effect appears based on . The low-temperature specific heat of NpPdAl can be explained with the superposition of the heavy fermion state and localized Schottky anomaly, where the total entropy was maintained ln3 for pseudo-triplet state. The -coupling scheme of AnPdAl can be described by the corresponding - coupling scheme, where Pu and Np are the hole version of Ce and Pr. The in NpPdAl is stabilized with the same mechanism as in PrTX, both exhibit the unconventional superconductivity.