作　　者： ; ; ; ; ;

机构地区： 重庆师范大学物理与电子工程学院

出　　处： 《功能材料》 2016年第4期119-124,128,共7页

摘　　要： 采用基于密度泛函理论(DFT)的第一性原理平面波超软赝势方法,结合局域自旋密度近似和Hubbard U修正,对不同Co离子自旋态下及Ga掺杂LaCoO_3的超晶胞体系进行了几何结构优化,计算并分析了它们的电子结构。结果表明,当Co离子处于低自旋态时,LaCoO_3为非磁绝缘性的绝缘体;当Co离子被激发到中间自旋态时,由于强烈的p-d轨道杂化作用,LaCoO_3转变成一个有磁性的半金属体;当Co离子处于高自旋态时,体系呈现金属铁磁性,磁矩由中间自旋态的0.91μB增大到高自旋态的2.2μB。Ga掺杂后,体系的Co3d态电子和Ga4p态电子以及O2p态电子在费米能级附近发生p-d轨道杂化,引入杂质带,形成受主能级,使体系的导电能力增强,体系呈现半金属铁磁性,其净磁矩为4.01μB。 The geometrical structures of LaCoO_3 with different Co^(3+) spin states and Ga doping were optimized by using the first principle density functional theory based on the full potential linearized augumented plane wave method and combined with local density approximation plus Hubbard U(LSDA+U).The electronic structures were calculated and discussed in details.LaCoO_3 is a non-magnetic insulator when Co3+is low spin state(LS).The strong hybridization of Co3 dand O2p electrons makes LaCoO_3+3becomes a magnetic half metal when Cotranslate to intermediate spin state(HS).It shows metallic ferromagnetic when Co3+is high spin state(HS).The magnetic moments increase form 0.91 of IS to 2.2μBof HS.Ga doping makes Co3 delectrons hybrid with Ga4p and O2p electrons,introduces the impurity bands to form acceptor energy level.The system enhances its conductivity and shows half metallic ferromagnetic.Its net magnetic moment is 4.01μB.

关 键 词： 掺杂 自旋态 电子结构 第 性原理

领　　域： [理学] [理学] [一般工业技术] [理学] [理学]