Structure determination in thin film Ba1-xLaxFe2As2: Relation between the FeAs4 geometry and superconductivity
Structure determination in thin film Ba1-xLaxFe2As2: Relation between the FeAs4 geometry and superconductivity
复制标题
DOI：
10.1103/physrevb.96.125116
复制
发表时间：
2017-09-11
影响因子：
3.7
通讯作者：
Hosono, Hideo
中科院分区：
文献类型：
--
作者：
Kobayashi, Kensuke;Nakao, Akiko;Hosono, Hideo
薄膜超导体Ba_（1-x）La_xFe_2As_2是通过在阻挡层内用La取代Ba而获得的BaFe_2As_2的第一种电子掺杂化合物。相反，在传统的电子掺杂Ba（Fe 1-xCox）（2）As-2中，掺杂剂（Co）被插入到导电层中。在上述两种化合物中，预期FeAs 4具有不同的形状或几何结构。然而，由于Ba 1-xLaxFe 2As 2是薄膜，因此在此研究其结构。为了澄清的几何形状的效果，我们利用一个最新的方法来确定的原子位置的Ba 1-xLaxFe 2As 2薄膜，使用同步辐射X射线衍射。我们建立了Ba 1-xLaxFe 2As 2中FeAs 4的几何形状表明掺杂后的系统变化，这与Ba（Fe 1-xCox）（2）As-2中的相反。然而，对于相同的掺杂量，超导转变温度几乎彼此一致。目前的结果与FeAs 4的几何形状强烈影响铁磷属元素的超导电性的建议。因此，我们建议，载流子密度是更重要的参数比FeAs 4的几何形状和电子相关性起着重要的作用，在电子掺杂的BaFe 2As 2的超导电性。
A thin film superconductor Ba1-xLaxFe2As2 is the first electron-doped compound of BaFe2As2 obtained by the substitution of Ba with La within a blocking layer. By contrast, in conventional electron-doped Ba(Fe1-xCox)(2)As-2, the dopant (Co) is inserted into the conduction layer. The different shapes, or geometries, of FeAs4 are expected in the two compounds above. However, the structure of Ba1-xLaxFe2As2 is investigated here because of being a thin film. To clarify the effect of the geometry, we make use of an up-to-date method to determine the atomic positions of the Ba1-xLaxFe2As2 thin film using synchrotron x-ray diffraction. We established that the FeAs4 geometry in Ba1-xLaxFe2As2 indicates a systematic variation upon doping, which is opposite to that in Ba(Fe1-xCox)(2)As-2. However, the superconducting transition temperatures nearly coincide with each other for the same amount of dopings. The present result contrasts with a suggestion that the FeAs4 geometry strongly influences the superconductivity in iron pnictides. Hence, we propose that the carrier density is the more important parameter than the FeAs4 geometry and that the electronic correlation plays a significant role in the superconductivity for the electron-doped BaFe2As2.