On the nature of superconductivity in the anisotropic dichalcogenide NbSe2{CoCp2}x
On the nature of superconductivity in the anisotropic dichalcogenide NbSe2{CoCp2}x
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DOI：
10.1088/0953-8984/27/15/155701
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发表时间：
2015-03
期刊：
影响因子：
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通讯作者：
E. Scheidt;M. Herzinger;Andreas Fischer;Dominik Schmitz;J. Reiners;Franz Mayr;F. Loder;M. Baenitz;Wolfgang Scherer
中科院分区：
文献类型：
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作者：
E. Scheidt;M. Herzinger;Andreas Fischer;Dominik Schmitz;J. Reiners;Franz Mayr;F. Loder;M. Baenitz;Wolfgang Scherer
我们详细研究了弱钉扎准二维超导体2H-NbSe_2及其插层变体NbSe_2{CoCp_2}0.26的超导性质。2H-NbSe2与有机金属施主分子钴(CoCp2)的插层对层内的超导性质几乎没有影响。然而，由于主晶格的层间距在c方向上扩展了约两倍，垂直于层的性质发生了显著变化。特别是，超导各向异性因子Γ从母体化合物2H-NbSe_2的3.3%增加到插层物种的4.4%。因此，NbSe2{CoCp2}0.26是分析各向异性如何影响层状二盐化合物超导机制的一个很好的候选者，也是评价文献中提出的解释2H-NbSe2各向异性的各种模型的一个很好的候选者。虽然两能隙模型和各向异性单能隙模型是描述低维二盐类化合物中ΔC/T与T2几乎线性相关的相互竞争的概念，但我们的比较研究表明，具有各向异性费米面的单能隙模型足以定性地捕捉我们样品中的ΔC/T(T)行为。
We present a detailed study of the superconducting properties of the weakly pinned, quasi-two-dimensional superconductor 2H-NbSe2, and its intercalated variant NbSe2{CoCp2}0.26. The intercalation of 2H-NbSe2 with the organometallic donor molecule cobaltocene (CoCp2) hardly affects the superconducting properties within the layers. However, the properties perpendicular to the layers change significantly due to the large expansion of the layer spacings of the host lattice in the c-direction by a factor of about two. In particular, the superconducting anisotropy factor Γ increases from 3.3 in the parent compound 2H-NbSe2 up to 4.4 in the intercalated species. Therefore, NbSe2{CoCp2}0.26 is an excellent candidate to analyze how the anisotropy effects the superconducting mechanism in layered dichalcogenides, and to evaluate the various models proposed in the literature to account for the anisotropy in 2H-NbSe2. While a two-gap model and an anisotropic single-gap model are competing concepts to describe the almost linear T2-dependence of ΔC/T in low-dimensional dichalcogenides, our comparative study suggests that a single-gap model with an anisotropic Fermi-surface is sufficient to capture the ΔC/T(T) behavior in our samples qualitatively.