插层三元铁硒超导体的电子结构和磁性质的理论研究  

Theoretical study of the electronic structures and magnetic properties of intercalated ternary iron-selenide superconductors

作　　者：卢仲毅[1] 闫循旺[1,2] 高淼[1] 向涛[2,3] 

机构地区：[1]中国人民大学物理系,北京100872 [2]中国科学院理论物理研究所,北京100190 [3]中国科学院物理研究所,北京100190

出　　处：《物理》2011年第8期527-534,共8页Physics

基　　金：国家自然科学基金(批准号:10725419)资助项目

摘　　要：最近发现的插层三元铁硒超导体AyFexSe2(A=K,Rb,Cs和/或Tl)显示诸多新颖现象.为了澄清这些现象,作者分别计算了没有铁空位的基于完整四方FeSe层的AFe2Se2,含有四分之一铁空位的4×2或2×2超结构的AFe1.5Se2,以及含有五分之一铁空位的槡5×槡5超结构的A0.8Fe1.6Se2三种情况下的电子结构和相应的磁构型,发现AFe2Se2是双共线反铁磁的半金属,而AFe1.5Se2和A0.8Fe1.6Se2则是分别具有数十和数百毫电子伏特能隙的反铁磁半导体,并分别处于共线反铁磁长程序和区块化棋盘反铁磁长程序中.作者还分析和讨论了AyFexSe2的这些基本电子结构可能对超导性质的影响.The newly discovered intercalated ternary iron-selenide superconductors AyFexSe2 （A=K, Rb, Cs, and/or Tl） show novel phenomena. To clarify these phenomena, we have carried out first-principles electronic structure calculations on AFe2Se2 with perfect tetragonal FeSe layers, AFe1.5Se2with one-quarter Fe vacancies ordered in the 4×2 or 2×2 superstructure, and A0.8Fe1.6Se2 with one-fifth Fe vacancies in the 5 × 5 superstructure. We find that the AFe2Se2 compounds are bi-collinear antiferromagnetic semimetals, while both AFe1.5Se2 and A0.8Fe1.6Se2 are antiferromagnetic semiconductors with band gaps of dozens and hundreds of meV, respectively; their ground states are in a collinear antiferromagnetic order and blocked checkerboard antiferromagnetic order, respectively. The underlying physics is discussed.

关 键 词：铁基超导体 反铁磁半金属 三元铁硒化合物 反铁磁半导体 电子结构计算 

分 类 号：O511.4[理学—低温物理]