第一原理研究Mn掺杂LiNbO_3晶体的磁性和光吸收性质  

Study on magnetic and optical properties of Mn-doped LiNbO_3 by using the first principles

作　　者：王藩侯[1] 杨俊升[1] 黄多辉[1] 曹启龙[1] 袁娣[1,2] 

机构地区：[1]宜宾学院计算物理四川省高等学校重点实验室,宜宾644007 [2]宜宾学院物理与电子工程学院,宜宾644007

出　　处：《物理学报》2015年第9期462-467,共6页Acta Physica Sinica

基　　金：四川省教育厅科研基金(批准号:13ZA0198);宜宾市重点科技资助项目(批准号:2014GY018);宜宾学院计算物理四川省高等学校重点实验室开放课题基金(批准号:JSWL2014KFZ02)资助的课题~~

摘　　要：采用基于密度泛函理论和局域密度近似的第一性原理分析了Mn掺杂LiNbO3晶体的结构,磁性,电子特性和光吸收特性.文中计算了Mn占据Li位和Nb位体系的形成焓,对应的形成焓分别为-8.340 e V/atom和-8.0062 eV/atom,也就意味着Mn原子优先占据Li位.这也就意味着Mn原子占据Li位的掺杂LiNbO3晶体结构更稳定.磁性分析的结果显示,其对应磁矩也比占据Nb位的高.进一步分析磁性的来源,自旋态密度结果显示:Mn掺杂LiNbO3晶体的磁性主要源于掺杂原子Mn,Mn原子携带的磁矩高达4.3μB,显示出高自旋结构.由于Mn-3d与近邻O-2p及次近邻Nb-4d轨道的杂化作用,计算表明:诱导近邻O原子及次近邻Nb原子产生的磁矩对总磁矩的贡献较小.通过光学吸收谱的分析,得出在可见光区Li位被Mn原子替代以后显示出更好的光吸收响应相比于Nb位.本文还分析了O空位对于LiNbO3晶体磁性与电子性质的影响,结果显示O空位的存在可以增加Mn掺杂LiNbO3体系的磁性.According to density functional theory of first-principles calculation theory, we study systematically the structure, magnetism, electronic and optical properties of Mn-doped LiNbO3. The enthalpies of formation of LiNbO3, when substituting Li and Nb with Mn, are -8.340 and -8.0062 eV/atom, respectively. This means that the LiNbO3 after substitution of Li with Mn is more stable than that of Nb with Mn. And the magnetic moments of LiNbO3 in the substitution of Li with Mn is higher than that in substitution of Nb with Mn. Results of the density of states calculation show that the magnetism comes from Mn atom, and its magnetic moments is 4.3 μs. The rest of the magnetic moments may come from the contribution of the O and Nb atoms, because of the interactions of Mn-3d orbit with the O-2p and Nb-4d orbits. Optical absorption spectra show an improved optical response in the visible range in LiNbO3 by substituting Li with Mn. Results of analysis of oxygen vacancy in LiNbO3 show that oxygen vacancy can improve the magnetic moments of Mn-doped LiNbO3 system.

关 键 词：第一性原理 LINBO3 MN掺杂 光学吸收 

分 类 号：O469[理学—凝聚态物理]