Fig. 1. Crystal structure of LFA film.LFA的晶体结构

Fig. 2. Four possible kinds of magnetic structures of Fe ion in LFA thin films: (a) Striped-type ferromagnetic order; (b) striped-type antiferromagnetic order; (c) checkerboard-type ferromagnetic order; (d) checkerboard-type antiferromagnetic order. The arrows represent the directions of electronic spins.LFA薄膜中Fe离子可能的四种磁性结构　(a) 条形铁磁; (b)条形反铁磁; (c) 棋盘形铁磁; (d) 棋盘形反铁磁; 箭头表示自旋方向

Fig. 3. Relative energies of different magnetic states varying with lattice constant of LFA thin film.LiFeAs薄膜中四种磁性结构的相对能量随晶格常数的变化

Fig. 4. The band structure of LFA superconductor thin film (AFM-2a magnetic states) under different strains: (a) Nostrained effect; (b) compressive strain (−3%); (c) tensile strain (3%).LFA超导薄膜AFM-2a磁性结构在不同应变条件下的能带结构　(a)无应变; (b) 压应变(−3%); (c) 张应变(3%)

Fig. 5. The density of electronic states of different ions in LFA superconductor thin film under different strains: (a) Nostrained effect; (b) compressive strain (−3%); (c) tensile strain (3%).LFA超导薄膜在不同应变条件时各离子的电子态密度　(a) 无应变; (b) 压应变(−3%); (c) 张应变(3%)

Fig. 6. The tetrahedral structure distortion of As centered on Fe ions and 3d orbital energy splitting of Fe ions: (a) Tabular tetrahedron without strain effect; (b) the distorted regular tetrahedron under compressive strain effect.以Fe离子为中心的As四面体结构畸变与3d轨道能级分裂　(a) 无应变时扁平的四面体; (b) 压应变作用下畸变后的正四面体

Table 1. Energy of unit cell of the iron-based superconductor thin film LFA in different magnetic structures.

Table 2. Magnetic moments of Fe ions of LFA thin films under different strains.