NMR/NQR study on the superconductivity and magnetism of Pu compounds

NMR/NQR測定法によるPu化合物の磁性と超伝導の研究

安岡 弘志; Koutroulakis, G.*; 中堂 博之 ; Tobash, P. H.*; Richmond, S.*; Bauer, E. D.*; Ronning, F.*; Thompson, J. D.*; Clark, D. L.*

Yasuoka, Hiroshi; Koutroulakis, G.*; Chudo, Hiroyuki; Tobash, P. H.*; Richmond, S.*; Bauer, E. D.*; Ronning, F.*; Thompson, J. D.*; Clark, D. L.*

NMR/NQR studies on the physical properties of the first In analog of the PuMGa (M=Co, Rh) family of superconductors, PuCoIn are reported. With its about 30 larger unit cell volume than PuCoGa, the characteristic spin-fluctuation energy scale of PuCoIn is three to four times smaller than that of PuCoGa, which suggests that the Pu 5f electrons are in a more localized state relative to PuCoGa. This raises the possibility that the high superconducting transition temperature Tc = 18.5 K in PuCoGa stems from proximity to a valence instability, while superconductivity at Tc =2.5 K in PuCoIn is mediated by antiferromagnetic spin fluctuations associated with a quantum critical point. The temperature dependence of 1/T for 3 line of the In(II) site in PuCoIn has been measured in a wide temperature range.