锆酸锶掺Co后磁性质的第一性原理研究  

First-principles study on the ferromagnetism of Co-doped SrZrO_3

作　　者：唐春红[1,2] 吴庆春[1] 崔云康[1] 

机构地区：[1]南京工程学院非线性物理研究所,南京211167 [2]南京大学物理学院固体微结构国家重点实验室,南京210093

出　　处：《南京大学学报（自然科学版）》2014年第2期143-147,共5页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金(51002075;51172067);省高校;学院自然科学基金(12KJB510004;ZKJ201204;CKJA201207)

摘　　要：本文使用在位库仑作用、局域密度近似下的投影缀加平面波方法,计算了钙钛矿材料锆酸锶（SrZrO3）正交相掺Co前后的晶体结构、电子能带结构及掺Co后的磁性质.结果表明：当Co Co之间的间距L为0.4097 nm,即最近邻,且体系为铁磁构型时对应的总能最低,表明 Co 掺杂进入钙钛矿 B位后,容易出现 Co 离子的团簇聚集,出现铁磁性；电子能带结构图显示Co部分替代Zr4＋后变为 Co4＋（3d5）,相对于标准化合价的 Co3＋（3d6）,有一条空的d轨道未占据,又由于掺杂Co后其d轨道与近邻O 的p轨道有强烈杂化,有部分Co的d轨道及O 的部分p轨道越过价带进入带隙,在0~2.60 eV之间,自旋向上出现3条Co 3d能带,自旋向下出现7条 Co 3d能带,且导带底向低能移动；部分Co离子替代钙钛矿B位的Zr4＋后,体系出现磁性,由于 Co 离子形式化合价为＋3,替代 Zr4＋后,这种空穴掺杂将在价带顶引入空的掺杂能级；态密度结果表明该能级为 Co4＋离子部分空的d轨道,通过 O 的p轨道,造成体系中Co3＋、Co4＋离子的出现,而它们之间的双交换耦合使得体系出现铁磁性.The structural,electronic properties,and the ferromagnetism of Co-doped orthorhombic SrZrO3 are calculated using the first-principles methods,which are performed within the density functional theory（DFT）using the projector augmented wave（PAW）implemented in the Vienna ab initio Simulation Package（VASP）,and the exchange-correlation potential is treated in the local density approximation using the Ceperly-Alder scheme.SrZrO3 has been the subject of investigations because of its technological applications.For instance,the wide band gap and high dielectric constant of SrZrO3 can be used in the electronic industry,and its refractory properties are of interest in hightemperature applications.The first-principles methods have been a powerful tool for obtaining accurate ground state and indicating the relevance between the microscopic structure and the properties.The lattice parameters and atomic positions are relaxed until the total energy changed by less than 10-5 eVper conventional cell and residual force is smaller than 0.01 eV/？.All the calculations reach good convergence.The calculated results show that the Zr atoms in B sites of perovskite structure substituted by Co atoms induce the ferromagnetism in the SrZr0.875 Co0.125＆amp;nbsp;O3 .The results showed that,when the spacing between the Co Co is 0.4097 nm,i.e.nearest neighbor,and the system is the the ferromagnetic configuration,the calculating engery is corresponding to the minimum total energy, which indicate that the Co dope into the perovskite B bit to come into being the Co ion clusters and to appear ferro-magnetic.The electronic band structure diagram states clearly that the Co,replacing partly Zr4＋,becomes the Co4＋（3d5 ）,which has an empty dorbital not being occupied relativing to the standardized aggregate price of Co3＋（3d6 ）.Because of doped Co dorbitals and Op orbitals have a strong hybrid to shift up the top of the valence band and shift down the bottom of the conduction band.It means that the doped of Co reduces the band g

关 键 词：电子能带结构 磁性 第一性原理 

分 类 号：O482.5[理学—固体物理]