Vertical-Strain Effect on the Band Structures of Sr(Ti<sub>0.875</sub>Fe<sub>0.125</sub>)O<sub>3</sub> Epitaxial Thin Films

本文采用密度泛函理论框架下考虑强关联效应的广义梯度近似方法(GGA + U)研究了SrTi1-xFexO3(x = 0.125)薄膜的能带结构，又利用c轴晶格常数拉伸或压缩模拟了SrTi0.875Fe0.125O3薄膜中的垂直张应变和压应变。在基态晶胞结构下，Fe掺杂离子导致了晶胞内空间电荷密度重新排布，并使得非磁性离子周围出现了磁化密度分布。同时借助不同强度的垂直应变作用，实现了SrTi0.875Fe0.125O3薄膜能带结构的连续变化。进而发现垂直张应变能够在很大程度上改善SrTi0.875Fe0.125O3薄膜的半金属特性。 The calculations were performed by means of the generalized gradient approximation with on-site coulomb correlation corrections (GGA + U) within the framework of density functional theory (DFT) to study the band structures of SrTi1-xFexO3(x = 0.125) thin films, and the vertical tensile and compressive strain were simulated by the expansion of the out-of-plane crystal lattice in the SrTi0.875Fe0.125O3 films. In the stable cell of SrTi0.875Fe0.125O3, the introduction of doped Fe ions led to the re-arrangement of the charge density in the supercell, and the magnetization density distribution occurred around the non-magnetic ions. Meanwhile, the band structures could be continuously tuned by the different values of vertical strain. Furthermore, the vertical tensile strain can largely improve the half-Metallic behavior of the SrTi0.875Fe0.125O3 films.