钙钛矿超晶格材料挠曲电效应的理论计算  

First-principles study on the flexoelectric effect of perovskite superlattice

作　　者：王继光 陈许敏 李珑玲 王越昊 WANG Jiguang;CHEN Xumin;LI Longling;WANG Yuehao(School of Sciences,Hangzhou Dianzi University,Hangzhou Zhejiang 310018,China)

机构地区：[1]杭州电子科技大学理学院,浙江杭州310018

出　　处：《杭州电子科技大学学报（自然科学版）》2023年第2期76-83,共8页Journal of Hangzhou Dianzi University：Natural Sciences

基　　金：国家自然科学基金资助项目(11874011)。

摘　　要：运用密度泛函理论的第一性原理研究SrTiO_(3)和PbTiO_(3)所构成的钙钛矿超晶格材料中纵向和剪切挠曲电系数。对不同尺寸的钙钛矿超晶格施加应变后,分析弛豫后的钙钛矿超晶格中原子位移及应变,运用密度泛函微扰理论计算SrTiO_(3)/PbTiO_(3)钙钛矿超晶格单胞中各原子的伯恩有效电荷。研究结果表明,构建的钙钛矿超晶格材料的纵向挠曲电系数为,比单晶SrTiO_(3)和单晶PbTiO_(3)材料分别减小了7.6%和19.5%;钙钛矿超晶格材料的剪切挠曲电系数为,比单晶SrTiO_(3)材料提升了30.0%。因此,构建的钙钛矿超晶格材料具有较高的剪切挠曲电效应。Flexoelectricity describes the linear response of electrical polarization to a strain gradient.The flexoelectric effect is negligible at macro-level.However,it could be significantly enhanced in nanoscale dielectric material.It is of great interest to investigate thin films with high flexoelectricity for their potential applications in functional devices.In this paper,both the longitudinal and shear flexoelectric coefficients of the thin films,where are built by SrTiO_(3) and PbTiO_(3) in series with different superlattice size,have been theoretically investigated by first-principles based on density of function theory.The atomic displacement,polarization and born effective charge for each atom in the superlattice have been analyzed by the density of perturbation function theory.The results show that longitudinal flexoelectric coefficient in the superlattice is-0.33 nC/m,which is 7.6%and 19.5%less than that of single crystal SrTiO_(3) and PbTiO_(3),respectively.However,the shear flexoelectric coefficient is increased to-8.58 nC/m,which is 30%larger than that of single crystal SrTiO_(3).The theoretically improved shear flexoelectricity for the superlattice provides a potential approach for the experimental fabrication of thin films for possible future applications.

关 键 词：挠曲电效应 超晶格 第一性原理 伯恩有效电荷 

分 类 号：O469[理学—凝聚态物理]