第一性原理计算Fe掺杂LiMgP新型稀磁半导体的半金属铁磁性  

First-principles calculation of half metallic ferromagnetism of Fe doped LiMgP new diluted magnetic semiconductor

作　　者：陈婷 庞军 何红 杜颖妍 向朝凯 贾倩 刘焦 于越 杜成旭 毋志民 CHEN Ting;PANG Jun;HE Hong;DU Yinyan;XIANG Chaokai;JIA Qian;LIU Jiao;YU Yue;DU Chengxu;WU Zhimin(Chongqing Key Laboratory of Photoelectric Functional Materials, College of Physics andElectronic Engineering, Chongqing Normal University, Chongqing 401331, China)

机构地区：[1]重庆师范大学物理与电子工程学院光电功能材料重庆市重点实验室

出　　处：《功能材料》2020年第2期2117-2125,共9页Journal of Functional Materials

基　　金：重庆市自然科学基金面上资助项目(cstc2019jcyj-msxmX0251);重庆师范大学教学名师培育计划资助项目(02030307-0003);重庆市高校创新团队计划资助项目(CXTDX201601016);国家大学生创新创业训练计划资助项目(201810637002)

摘　　要：采用基于密度泛函理论的广义梯度近似平面波超软赝势法,对不同离子浓度配比的Fe掺杂LiMgP新型稀磁半导体进行结构优化,计算并分析了体系的电子结构、半金属铁磁性、重叠电荷布局及体心离子附近各离子的电参数。结果表明Fe掺杂LiMgP能够得到性能优良的半金属铁磁体,具有大的半金属能隙及可控的电磁性质,有望成为一种极具应用潜力的自旋电子学器件材料。纯LiMgP体系中化学键为极化的共价键,Fe的掺入形成了比Mg-P更强的Fe-P共价键,表现出优异的半金属铁磁性且具有大的半金属能隙0.500 eV,Fe离子与Li、Mg、P3种离子之间的相互作用使得它们的轨道电子数减少。Li过量时,形成能最低,结构最稳定,带隙值较单掺Fe时明显减小,而体系的半金属性明显减弱,填隙的Li原子使得轨道之间的相互作用减弱,Fe-P键的重叠电荷布局和体系净磁矩的值最小。Li不足时体系变为金属铁磁性,体系中离子的轨道电子数最少,参与轨道杂化的电子数最多,Fe和P原子之间的电子云分布最密集且共用电子对偏移程度最小,Fe-P键重叠电荷布局达到最大值0.78,键长达到最小值,体系净磁矩最大。The geometry structures of Li1±y(Mg1-xFex)P(x=0.125;y=0,0.125)were optimized by adopting the first-principles calculation of plane wave ultra-soft pseudo-potential technology based upon the density function theory(DFT)。Then the electronic structures,formation energies,density of states,overlapping charge distribution and electrical parameters of ions near the body central ions were calculated。The results reveal that Fe doped LiMgP was an outstanding half-metallic ferromagnet with large half-metallic energy gap of 0.500 eV and controllable electromagnetic properties,which was expected to be a good candidate of spintronic devices with great potential application。The chemical bonds of pure LiMgP were polarized covalent bonds。Fe doping led to form stronger Fe-P covalent bond than that of Mg-P。The interaction between Fe ions and Li,Mg,P ions reduced their orbital electronic number。When Li was excessive,the formation energy was the lowest and the structure was the most stable。The band gap value was decreased greatly compared with that of Fe doped alone,meanwhile,the half-metallicity was significantly weakened。Interstitial Li atoms weakened the interaction between orbits,and the overlapping charge distribution of Fe-P bonds and the net magnetic moment of the system were the smallest。When Li was insufficient,the system became metallic ferromagnetism。The orbital electronic number of the ions was the smallest,but the hybrid orbital electronic number was the largest。The distribution of electron clouds between Fe and P atoms was the densest,and the offset degree of the shared electron pairs was the smallest。The overlapping charge distribution of Fe-P bond reached the maximum of 0.78,the bond length reached the minimum,and the net magnetic moment of the system was the biggest.

关 键 词：Fe掺杂LiMgP 半金属铁磁性 重叠电荷布局 差分电荷密度 轨道电子数 

分 类 号：O472[理学—半导体物理] O469[理学—物理]