FeAs- single layer is tested as a simple model for LaFeAsO and BaFe2As2 based on first-principles calculations using generalized gradient approximation (GGA) and GGA+U. The calculated single- layer geometric and electronic structures are inconsistent with that of bulk materials. The bulk collinear antiferromagnetic ground state is failed to be obtained in the FeAs- single layer. The monotonous behavior of the Fe-As distance in z direction upon electron or hole doping is also in contrast with bulk materials. Our results indicate that, in LaFeAsO and BaFe2As2, interactions between FeAs layer and other layers beyond simple charge doping are important, and a single FeAs layer may not represent a good model for Fe based superconducting materials.
The role of different negatively charged layers in Ca10(Fe1-xPtxAs)10(Pt3+yAs8) and superconductivity at 30 K in electron-doped (Ca0.8La0.2)10(FeAs)10(Pt3As8)
Tuning the magnetism of the top-layer FeAs on BaFe$_{2}$As$_{2}$(001): First-principles study
用第一性原理电子结构计算方法研究了BaFe $_{2}$ As $_{2}$（001）表面的磁性.我们发现，对于As终止表面的磁性基态的顶层FeAs是在交错的二聚体反铁磁（AFM）秩序，而Ba终止表面的共线（单条纹）AFM秩序是最稳定的。当Ba或K原子覆盖到As表面时，计算得到的BaFe $_{2}$ As $_{2}$（001）上顶层FeAs的原子力显微镜能级差减小，表明自旋涨落增强.为了确定新的交错的二聚体AFM秩序的终止，我们模拟了扫描隧道显微镜（STM）图像为这个状态，它显示了不同的$\sqrt{2}\times\sqrt{2}$图案的情况下，半钡覆盖。我们的研究结果表明：（1）表面掺杂可以有效地调节BaFe $_{2}$ As $_{2}$（001）上顶层FeAs的磁性;（2）表面终止和顶层FeAs中的原子力显微镜有序度都可以影响BaFe $_{2}$ As $_{2}$（001）的STM图像。
Synthesis, Structure and Properties of Tetragonal Sr2M3As2O2 (M3 = Mn3, Mn2Cu and MnZn2) Compounds Containing Alternating CuO2-Type and FeAs-Type Layers
We report observation of strong magnetic proximity coupling in a heterostructured superconductor Sr$_2$VO$_3$FeAs, determined by the upper critical fields $H_{c2}(T)$ measurements up to 65 T. Using the resistivity and the radio-frequency measurements for both $H \parallel ab$ and $H \parallel c$, we found a strong upward curvature of $H_{c2}^c(T)$, together with a steep increase of $H_{c2}^{ab}(T)$ near $T_c$, yielding the anisotropic factor $γ_H=H_{c2}^{ab}/H_{c2}^c$ up to $\sim$ 20, the largest value among iron-based superconductors. These are attributed to the Jaccarino-Peter effect, rather…
Sr$_2$VO$_3$FeAs: A Nanolayered Bimetallic Iron Pnictide Superconductor
在铁磷属元素化物超导体中，对于磁有序机制和非常规的序参量特征，统一的概念之一是近似嵌套的电子和空穴费米面。利用密度泛函方法对SrFe $_2$ P $_2$中的费米面进行了正确的预测，我们发现最近报道的超导SrPDMATHABMM VO $_3$ FeAs（$T_c$ =37 K，磁性和超导电性之间没有明显的竞争）具有与以前的铁磷属元素化物不同的费米面几何形状和性质.中间层（V双层）产生穿过费米能级的能带。耦合到FeAs层是小的，除了沿区域边界的相互作用，但是，耦合退化的费米面嵌套。Sr $_2$ VO $_3$ FeAs，其开放的壳层原子的交替层，值得进一步仔细研究，这将有助于理解铁磷属化合物的性质的起源。
Electronic band structure of novel tetragonal BiOCuS as a parent phase for novel layered superconductors
最近，合成了四元BiOCuS，并宣布其为具有Fe-氧氮化合物相关结构的新超导体系。本文基于第一性原理FLAPW-GGA计算，首次研究了BiOCuS的结构参数、能带结构、态密度和电子密度分布。我们的研究结果表明，与相关的类金属FeAs系统不同，BiOCuS相的行为与计算的间接带隙在约0.48 eV的离子半导体。BiOCuS的超导电性可以完全通过掺杂该相来实现。我们的初步结果表明，作为空穴掺杂的结果，[CuS]块成为导电由于混合Cu 3d + S 3 p带位于费米能级附近。对于空穴掺杂BiOCuS的费米面采用准二维字符，类似于FeAs SC。
Electronic band structure and inter-atomic bonding in layered 1111-like Th-based pnictide oxides ThCuPO, ThCuAsO, ThAgPO, and ThAgAsO from first principles calculations
Electronic band structure and Fermi surface for new layered superconductor LaO0.5F0.5BiS2 in comparison with parent phase LaOBiS2 from first principles
