Crossover from weak to strong pairing in unconventional superconductors
Crossover from weak to strong pairing in unconventional superconductors
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DOI：
10.1103/physrevb.83.214520
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发表时间：
2011-06-29
影响因子：
3.7
通讯作者：
Hinkov, V.
中科院分区：
文献类型：
--
作者：
Inosov, D. S.;Park, J. T.;Hinkov, V.
超导体是根据它们的配对机制和耦合强度来分类的，以能隙2 δ与临界温度T-c的比值来衡量。我们提出了从简单金属到高T-c铜酸盐和铁酸盐的许多单带和多带超导体的2 δ /k(B)T(c)比的广泛比较。与最近提出的该比率在铁基超导体中的普遍性相反，我们发现化合物中的耦合范围从弱（接近BCS极限）到强（如铜酸盐），弥合了这两个极端之间的差距。此外，对于铁基和铜基材料，我们的分析揭示了间隙比和T-c之间的普遍相关性，这在传统超导体中没有发现，因此支持两个家族中常见的非常规配对机制。这一结果对铁镍化合物的一个重要影响是，决定共振阻尼的激子自旋共振模式和粒子-空穴连续体之间的能量分离不再与T-c无关。
Superconductors are classified by their pairing mechanism and the coupling strength, measured as the ratio of the energy gap, 2 Delta, to the critical temperature, T-c. We present an extensive comparison of the 2 Delta/k(B)T(c) ratios among many single-and multiband superconductors from simple metals to high-T-c cuprates and iron pnictides. Contrary to the recently suggested universality of this ratio in Fe-based superconductors, we find that the coupling in pnictides ranges from weak, near the BCS limit, to strong, as in cuprates, bridging the gap between these two extremes. Moreover, for Fe-and Cu-based materials, our analysis reveals a universal correlation between the gap ratio and T-c, which is not found in conventional superconductors and therefore supports a common unconventional pairing mechanism in both families. An important consequence of this result for ferropnictides is that the separation in energy between the excitonic spin-resonance mode and the particle-hole continuum, which determines the resonance damping, no longer appears independent of T-c.