双钙钛矿SrKFeWO_6的电子结构与磁性  

Electronic structure and magnetism of the double perovskite SrKFeWO_6

作　　者：张瑜[1] 刘拥军[1] 刘先锋[1] 江学范[2] 

机构地区：[1]扬州大学物理科学与技术学院,扬州225002 [2]常熟理工学院,江苏省新型功能材料重点建设实验室,常熟215500

出　　处：《物理学报》2010年第5期3432-3437,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10874021);江苏省高校自然科学研究项目(批准号:05KJB14047和06KJA43014)资助的课题~~

摘　　要：基于密度泛函理论框架下的第一性原理,采用考虑在位库仑作用的广义梯度近似(GGA+U)下的投影缀加波(PAW)方法,研究了具有双钙钛矿结构的Sr2FeWO6和SrKFeWO6材料的晶体结构、电子结构以及磁性性质.结构优化表明,K空穴掺杂稳定了FeO6及WO6八面体结构,Fe-O-W键角更加接近180°,有利于Fe-O-W-O-Fe超交换作用;对电子结构分析发现掺杂元素本身对总态密度贡献很小,空穴(p型)掺杂导致B位Fe离子的价态升高,磁性增强,Fe-O杂化增强,但B’位W离子的价态不发生改变,电子的迁移方式由掺杂前的Fe-W电荷转移变成了掺杂后电子在Fe-Fe之间的直接转移.The crystal structure,electronic structure and magnetism of the double perovskite Sr2FeWO6 and SrKFeWO6 have been investigated under the framework of density functional theory （ DFT） with the generalized gradient approximation taking into account the on-site Coulomb energy （ GGA ＋ U） using the projected augmented wave （ PAW） method. Structure relaxation results show that K doping of Sr2FeWO6 stabilizes FeO6,WO6 octahedra and makes the Fe—O—W angles close to 180°,indicating the enhancement of superexchange interaction. From the electronic structure calculation,it was found that the contribution to the total density of states （ DOS） from K itself is small. Due to the K doping,the valence and magnetic moment of B-site cation Fe are enhanced and the hybridization between Fe and O becomes stronger,as well as the band gap is enlarged. Nevertheless,it does not cause considerable change in B＇-site cation W. The process of transfer of electrons is dominated by Fe-Fe in SrKFeWO6compared with Fe-W charge transfer in Sr2FeWO6 before doping.

关 键 词：电子结构 磁性 SrKFeWO6 双钙钛矿 

分 类 号：O482.5[理学—固体物理]