Spin resonance peak in Fe-based superconductors with unequal gaps
Spin resonance peak in Fe-based superconductors with unequal gaps
复制标题
不等间隙铁基超导体中的自旋共振峰
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Y. Togushova
中科院分区：
文献类型：
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作者：
M. Korshunov;V. Shestakov;Y. Togushova
本文在具有两个不等能隙$Delta_L$和$Delta_S$的多带模型下，研究了铁基材料在不同费米面口袋上超导态的自旋共振。我们表明，由于差距的间接性质进入自旋磁化率在嵌套波矢量$mathbf{Q}$的总间隙$ 裸磁化率中的ildeDelta由两个不同费米面片上的能隙之和确定，所述两个费米面片由$mathbf{Q}$连接。对于大多数铁磷属化物和硫属化物的费米表面几何特征，间接能隙为： ildeDelta = Delta_L + Delta_S$或$ ildeDelta = 2Delta_L$。在$s_{++}$状态下，自旋激发低于$ ildeDelta$是不存在的，除非假设额外的散射机制。自旋共振出现在超导态的$s_pm$频率为$omega_R leq ildeDelta$.与现有的非弹性中子散射数据的比较证实，所看到的是真正的自旋共振，而不是固有的峰的$s_{++}$状态。
We study the spin resonance in superconducting state of iron-based materials within multiband models with two unequal gaps, $Delta_L$ and $Delta_S$, on different Fermi surface pockets. We show that due to the indirect nature of the gap entering the spin susceptibility at the nesting wave vector $mathbf{Q}$ the total gap $ ildeDelta$ in the bare susceptibility is determined by the sum of gaps on two different Fermi surface sheets connected by $mathbf{Q}$. For the Fermi surface geometry characteristic to the most of iron pnictides and chalcogenides, the indirect gap is either $ ildeDelta = Delta_L + Delta_S$ or $ ildeDelta = 2Delta_L$. In the $s_{++}$ state, spin excitations below $ ildeDelta$ are absent unless additional scattering mechanisms are assumed. The spin resonance appears in the $s_pm$ superconducting state at frequency $omega_R leq ildeDelta$. Comparison with available inelastic neutron scattering data confirms that what is seen is the true spin resonance and not a peak inherent to the $s_{++}$ state.