铁电垒磁性隧道结中的非对称界面效应

项目名称： 铁电垒磁性隧道结中的非对称界面效应

项目编号： No.11274054

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 吴银忠

作者单位： 苏州科技学院

项目金额： 75万元

中文摘要： 非对称界面是铁电垒磁性隧道结制备过程中不可避免的，并会对隧道结的输运性质产生重要影响。本课题采用基于密度泛函理论的第一性原理方法，研究不对称界面的形成机制以及它对实验条件的依赖(如基底应力、制备氧压、沉积厚度), 系统分析非对称界面对铁电垒磁性隧道结界面电子结构、磁结构、磁电耦合的影响。同时通过计算铁电垒的本征双势阱，考察非对称界面对铁电垒临界厚度和自发极化的影响。进一步利用第一性原理计算得到的参数，结合热力学唯像理论和量子隧穿理论研究非对称界面对隧道结电荷输运和自旋输运性质的影响。更进一步通过在隧道结界面处插入过渡磁性金属氧化层，系统探究如何增强界面磁电耦合，寻找在铁电垒中获得高自发极化、增强铁电垒磁性隧道结电致电阻效应和磁致电阻效应的有效途径。为实验制备高性能多态存储器和高性能自旋电子器件提供设计方案和理论依据。

中文关键词： 铁电隧道结；界面效应；界面掺杂；隧穿电致电阻；铁电极化

英文摘要： Asymmetric interfaces, in general, exist inevitably in the magnetic tunneling junction with a ferroelectric barrier, such as the different terminal atomic layers within the barrier, and asymmetric interfaces will have important influence on the transport properties of the junction. Based on the first-principles calculations, the formation mechanism of stable interface structures and its dependence on experimental conditions are studied. Effects of asymmetric interfaces on the interfacial electronic structure, magnetic structure, magnetoelectric coupling are investigated. At the same time, by calculating the intrinsic double-well potential of the ferroelectric barrier, the critical thickness will be given for the junction with asymmetric interfaces. Further, using the parameters obtained from the first-principles calculations, and combining the thermodynamics phenomenological model and the quantum tunneling theory, effects of asymmetric interfaces on the charge transport and spin transport in the junction are simulated. By artificially inserting transition metal oxide layer in the interface, we try to find an effective way to enhance the interfacial magnetoelectric coupling, and to obtain large polarization, high tunneling electroresistance and tunneling magnetoresistance. Our studies can provide theoretical foun

英文关键词： Ferroelectric tunneling junction；interface effect；interface dopping；tunneling electroresistance；ferroelectric polarization