Isotope effect and the role of phonons in the iron-based superconductors
Isotope effect and the role of phonons in the iron-based superconductors
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DOI：
10.1103/physrevb.79.092503
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发表时间：
2008-11
影响因子：
3.7
通讯作者：
Y. Bang
中科院分区：
文献类型：
--
作者：
Y. Bang
我们用符号变化的S波($\ifmmod\pm\Else\TextPM\fI‘S’波)态的唯象双带模型研究了铁基超导体中声子的同位素效应。在这个平均场模型中，我们发现大同位素效应与S的模式、PM、否则、文本、S等波配对态及其高跃迁温度并不矛盾。原则上，大的声子同位素系数意味着大的声子耦合常数。然而，两个能带之间的非对称态密度大大提高了声子耦合常数$({\ensuremath{\lambda}}_{\text{ph}}\ensuremath{\approx}0.4)$的值，因此适中的声子耦合常数$\ensuremath{\alpha}(\ensuremath{\approx}0.4)$可以产生很大的相变温度和反铁磁致相互作用。
We studied the isotope effect of phonon in the Fe-based superconductors using a phenomenological two band model for the sign-changing $s$-wave ($\ifmmode\pm\else\textpm\fi{}s$-wave) state. Within this mean-field model, we showed that the large isotope effect is not inconsistent with the $\ifmmode\pm\else\textpm\fi{}s$-wave pairing state and its high transition temperature. In principle, a large phonon isotope coefficient $\ensuremath{\alpha}$ implies a large phonon coupling constant. However, the asymmetric density of states between two bands substantially enhances the value of $\ensuremath{\alpha}$, so that a moderate value of the phonon coupling constant $({\ensuremath{\lambda}}_{\text{ph}}\ensuremath{\approx}0.4)$ can produce a very large value of $\ensuremath{\alpha}(\ensuremath{\approx}0.4)$ as well as a high transition temperature together with an antiferromagnet-induced interaction.