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論文

Observation of $$^{239}$$Pu nuclear magnetic resonance

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 ($$^{239}$$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 $$^{239}$$Pu resonance from a solid sample of plutonium dioxide, PuO$$_2$$, subjected to a wide scan of external magnetic field values ($$B_0=3$$ 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 $$^{239}$$$$gamma$$$$_{rm n}$$(PuO$$_2$$)/2$$pi$$ to be 2.856 $$pm$$ 0.001 MHz/T. Assuming a free-ion value for the Pu$$^{4+}$$ hyperfine coupling constant, we estimated a bare $$^{239}$$$$gamma$$$$_{rm n}$$/2$$pi$$ value of approximately 2.29 MHz/T, corresponding to a nuclear magnetic moment of $$mu$$$$_{rm n}$$ $${approx}$$ 0.15 $$mu$$$$_{rm N}$$ (where $$mu$$$$_{rm N}$$ is the nuclear magneton).

口頭

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

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$$_5$$ (M=Co, Rh) family of superconductors, PuCoIn$$_5$$ are reported. With its about 30$$%$$ larger unit cell volume than PuCoGa$$_5$$, the characteristic spin-fluctuation energy scale of PuCoIn$$_5$$ is three to four times smaller than that of PuCoGa$$_5$$, which suggests that the Pu 5f electrons are in a more localized state relative to PuCoGa$$_5$$. This raises the possibility that the high superconducting transition temperature Tc = 18.5 K in PuCoGa$$_5$$ stems from proximity to a valence instability, while superconductivity at Tc =2.5 K in PuCoIn$$_5$$ is mediated by antiferromagnetic spin fluctuations associated with a quantum critical point. The temperature dependence of 1/T$$_1$$ for 3$$nu_Q$$ line of the In(II) site in PuCoIn$$_5$$ has been measured in a wide temperature range.

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