间隔层调控SrVO_(3)/SrTiO_(3)超晶格铁磁半金属-铁磁绝缘体转变  

Spacer-layer-tunable ferromagnetic half-metal-ferromagnetic insulator transition in SrVO_(3)/SrTiO_(3) superlattice

作　　者：房晓南 危芹 隋娜娜 孔志勇 刘静[2] 杜颜伶 Fang Xiao-Nan;Wei Qin;Sui Na-Na;Kong Zhi-Yong;Liu Jing;Du Yan-Ling(Information Engineering College,Shandong Management University,Jinan 250357,China;College of Intelligence and Information Engineering,Shandong University of Traditional Chinese Medicine,Jinan 250355,China)

机构地区：[1]山东管理学院信息工程学院,济南250357 [2]山东中医药大学智能与信息工程学院,济南250355

出　　处：《物理学报》2022年第23期355-365,共11页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:82174528);山东管理学院博士科研启动基金(批准号:SDMUD201901);山东管理学院科研启航计划(批准号:QH2020Z05)资助的课题.

摘　　要：本文利用基于密度泛函理论(DFT)的第一性原理计算研究了SrVO_(3)/SrTiO_(3)(111)超晶格的电子结构、电学和磁学性质.研究结果表明,SrVO_(3)/SrTiO_(3)(111)超晶格可通过调节间隔层SrTiO_(3)的厚度实现铁磁半金属-铁磁绝缘体的转变.SrVO_(3)亚层之间可以通过厚度为2个原子层的SrTiO_(3)间隔层发生层间耦合,超晶格呈现铁磁半金属态;当间隔层SrTiO_(3)的厚度等于3个原子层时,超晶格出现小的带隙(约0.28 eV);当间隔层SrTiO_(3)的厚度大于3个原子层时,超晶格出现较大带隙,呈现铁磁绝缘态.进一步对SrVO_(3)/SrTiO_(3)界面附近由于Ti-V混合导致的缺陷界面进行研究发现,界面附近的Ti-V混合对金属-绝缘体转变具有重要的影响:与理想界面相比,Ti-V混合的缺陷界面更能抑制层间耦合,诱导超晶格实现铁磁半金属-铁磁绝缘体的转变.本研究结果为SrVO_(3)/SrTiO_(3)(111)超晶格通过调控间隔层SrTiO_(3)层数实现铁磁半金属-铁磁绝缘体的转变提供了理论依据.In this work,the first-principle calculations based on density functional theory(DFT)are employed to investigate the electronic and magnetic properties of SrVO_(3)/SrTiO_(3)(111)superlattices.The studies show that the transition from ferromagnetic half-metal to ferromagnetic insulator can be achieved by adjusting the thickness of the spacer-layer SrTiO_(3).The interlayer coupling between the SrVO_(3) sublayers can occur across two unit-cell(uc)distance of SrTiO_(3),and the superlattice is ferromagnetic half-metal.When the SrTiO_(3) sublayers are 3uc,a small band gap(about 0.28 eV)appears in the superlattice.When the SrTiO_(3) sublayers are more than 3uc,the superlattice has a large band gap and exhibits ferromagnetic insulating state.Further studies show that the Ti-V mixed defects play an important role in realizing the transition of metal-insulator.Compared with the ideal interface,the Ti-V mixed interface can inhibit the interlayer coupling and induce the transition of ferromagnetic half-metal to ferromagnetic insulator.These results provide a theoretical basis for the transition of ferromagnetic half-metal to ferromagnetic insulator by adjusting the number of SrTiO_(3) layers in SrVO_(3)/SrTiO_(3)(111)superlattices.

关 键 词：超晶格 金属-绝缘体转变 铁磁半金属 铁磁绝缘体 

分 类 号：O469[理学—凝聚态物理]