Magnetic and electronic properties of the antiferromagnet NpCoGa 5
Magnetic and electronic properties of the antiferromagnet NpCoGa 5
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反铁磁体 NpCoGa 5 的磁性和电子特性
DOI：
10.1103/physrevb.69.184411
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发表时间：
2004
影响因子：
3.7
通讯作者：
G. Stewart
中科院分区：
文献类型：
--
作者：
E. Colineau;P. Javorský;P. Boulet;F. Wastin;J. Griveau;J. Rebizant;J. Sanchez;G. Stewart
超导 ${\mathrm{PuCoGa}}_{5}$ 化合物的 Np 对应物 ${\mathrm{NpCoGa}}_{5},$ 已通过磁化强度、电阻率、比热和 ${}^{237}\mathrm{Np}$ 进行了研究 M\"ossbauer 光谱测量。与钚化合物不同，${\mathrm{NpCoGa}}_{5}$ 没有显示出任何低至 $T=0.4\mathrm{K}$ 的超导性迹象，但低于以下的反铁磁序的开始 ${T}_{N}=47\mathrm{K}.$磁化实验证明${(B}_{c}=4.5\mathrm{T}$在$T=5\mathrm{K})$处向倾斜反铁磁体发生类似变磁的转变。电子有效质量为 ${\mathrm{NpCoGa}}_{5}$ 通过索末菲比热系数得到适度增强 $\ensuremath{\gamma}=64{\mathrm{mJ}\mathrm{}\mathrm{mol}}^{\ensuremath{-}1}{\mathrm{K}}^{\ensuremath{-}2},$相当于 ${\mathrm{PuCoGa}}_{5}.$ 从 M\"ossbauer 数据推断出 $0.84{\ensuremath{\mu}}_{B}$ 的有序 Np 矩以及 ${\mathrm{Np}}^{3+}$ 电荷态的出现。与 ${\mathrm{NpGa}}_{3}$ 的比较表明 ${\mathrm{NpCoGa}}_{5}$ 中的 $5f$ 电子有适度的离域。$与等结构 ${\mathrm{PuCoGa}}_{5}$ 的异同 讨论了 $\mathrm{Ce}M{\mathrm{In}}_{5}$ 化合物。
The Np counterpart of the superconducting ${\mathrm{PuCoGa}}_{5}$ compound, ${\mathrm{NpCoGa}}_{5},$ has been investigated by magnetization, resistivity, specific heat, and ${}^{237}\mathrm{Np}$ M\"ossbauer spectroscopy measurements. Unlike the plutonium compound, ${\mathrm{NpCoGa}}_{5}$ does not show any hint of superconductivity down to $T=0.4\mathrm{K}$ but the onset of antiferromagnetic order below ${T}_{N}=47\mathrm{K}.$ The magnetization experiments evidence a metamagnetic-like transition ${(B}_{c}=4.5\mathrm{T}$ at $T=5\mathrm{K})$ towards a canted antiferromagnet. The electronic effective mass in ${\mathrm{NpCoGa}}_{5}$ is moderately enhanced with a Sommerfeld specific heat coefficient $\ensuremath{\gamma}=64{\mathrm{mJ}\mathrm{}\mathrm{mol}}^{\ensuremath{-}1}{\mathrm{K}}^{\ensuremath{-}2},$ comparable to that of ${\mathrm{PuCoGa}}_{5}.$ An ordered Np moment of $0.84{\ensuremath{\mu}}_{B}$ and the occurrence of a ${\mathrm{Np}}^{3+}$ charge state were inferred from the M\"ossbauer data. Comparison with ${\mathrm{NpGa}}_{3}$ suggests a moderate delocalization of the $5f$ electrons in ${\mathrm{NpCoGa}}_{5}.$ Similarities and differences with the isostructural ${\mathrm{PuCoGa}}_{5}$ and $\mathrm{Ce}M{\mathrm{In}}_{5}$ compounds are discussed.