Impurity-induced in-gap state and Tc in sign-reversing s-wave superconductors: analysis of iron oxypnictide superconductors
Impurity-induced in-gap state and Tc in sign-reversing s-wave superconductors: analysis of iron oxypnictide superconductors
复制标题
DOI：
10.1088/1367-2630/11/3/035005
复制
发表时间：
2008-12
影响因子：
3.3
通讯作者：
Y. Senga;H. Kontani
中科院分区：
文献类型：
--
作者：
Y. Senga;H. Kontani
由于库珀对的带间散射，有望在氧磷族超导体中实现的符号反转全带隙超导态可能会受到非磁性杂质的显着影响。我们基于各向同性双能带 BCS 模型来研究这个问题：在氧磷族超导体中，带间杂质散射 I ′ 不等于带内杂质散射 I。在玻恩散射区，由于带间散射，Tc 的降低相当大，并且如果 I∼I ′，杂质引起的态密度 (DOS) 很突出。尽管杂质引起的 DOS 可以在 1/T1 中产生幂律温度依赖性，但它不可避免地伴随着 Tc 的大幅抑制。相反，在单一散射区域中，除了 I=I ′ 以外，杂质对 Tc 和 DOS 的影响都非常小。通过比较理论和实验，我们推测 s± 波间隙函数的各向异性程度很大程度上取决于化合物。
The sign-reversing fully gapped superconducting state, which is expected to be realized in oxypnictide superconductors, can be prominently affected by nonmagnetic impurities due to the interband scattering of Cooper pairs. We study this problem based on the isotropic two-band BCS model: in oxypnictide superconductors, the interband impurity scattering I ′ is not equal to the intraband one I. In the Born scattering regime, the reduction in Tc is sizeable and the impurity-induced density of states (DOS) is prominent if I∼I ′, due to the interband scattering. Although impurity-induced DOS can yield a power-law temperature dependence in 1/T1, it is inevitably accompanied by a sizeable suppression of Tc. In the unitary scattering regime, in contrast, the effect of impurities is very small for both Tc and DOS except at I=I ′. On comparing theory and experiments, we surmise that the degree of anisotropy in the s±-wave gap function strongly depends on the compound.