Ma J-Z, van Roekeghem A, Richard P, Liu Z-H, Miao H, Zeng L-K, Xu N, Shi M, Cao C, He J-B, Chen G-F, Sun Y-L, Cao G-H, Wang S-C, Biermann S, Qian T, Ding H
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Centre de Physique Théorique, Ecole Polytechnique, CNRS-UMR7644, 91128 Palaiseau, France.
Phys Rev Lett. 2014 Dec 31;113(26):266407. doi: 10.1103/PhysRevLett.113.266407.
The electronic structure of the iron-based superconductor Ba2Ti2Fe2As4O (Tc(onset)=23.5 K) has been investigated by using angle-resolved photoemission spectroscopy and combined local density approximation and dynamical mean field theory calculations. The electronic states near the Fermi level are dominated by both the Fe 3d and Ti 3d orbitals, indicating that the spacer layers separating different FeAs layers are also metallic. By counting the enclosed volumes of the Fermi surface sheets, we observe a large self-doping effect; i.e., 0.25 electrons per unit cell are transferred from the FeAs layer to the Ti2As2O layer, leaving the FeAs layer in a hole-doped state. This exotic behavior is successfully reproduced by our dynamical mean field calculations, in which the self-doping effect is attributed to the electronic correlations in the 3d shells. Our work provides an alternative route of effective doping without element substitution for iron-based superconductors.
利用角分辨光电子能谱以及结合局域密度近似和动力学平均场理论计算，对铁基超导体Ba2Ti2Fe2As4O（起始转变温度Tc = 23.5 K）的电子结构进行了研究。费米能级附近的电子态由Fe 3d和Ti 3d轨道共同主导，这表明分隔不同FeAs层的间隔层也是金属性的。通过计算费米面片所包围的体积，我们观察到了显著的自掺杂效应；即每晶胞有0.25个电子从FeAs层转移到Ti2As2O层，使FeAs层处于空穴掺杂状态。我们的动力学平均场计算成功再现了这种奇特行为，其中自掺杂效应归因于3d壳层中的电子关联。我们的工作为铁基超导体提供了一种无需元素替代的有效掺杂途径。
