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安岡 弘志; Koutroulakis, G.*; 中堂 博之; Richmond, S.*; Veirs, D. K.*; Smith, A. I.*; Bauer, E. D.*; Thompson, J. D.*; Jarvinen, G. D.*; Clark, D. L.*
Science, 336(6083), p.901 - 904, 2012/05
被引用回数:46 パーセンタイル:85.86(Multidisciplinary Sciences)The spin-1/2 plutonium-239 (Pu) nucleus should in principle be active in nuclear magnetic resonance spectroscopy. However, its signal has eluded detection for the past fifty years. Here, we report observation of a Pu resonance from a solid sample of plutonium dioxide, PuO, subjected to a wide scan of external magnetic field values ( to 8T) at a temperature of 4 Kelvin. By mapping the external field dependence of the measured resonance frequency, we determined the nuclear gyromagnetic ratio (PuO)/2 to be 2.856 0.001 MHz/T. Assuming a free-ion value for the Pu hyperfine coupling constant, we estimated a bare /2 value of approximately 2.29 MHz/T, corresponding to a nuclear magnetic moment of 0.15 (where is the nuclear magneton).
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.*
no journal, ,
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.