铁磁/铁电异质外延结构的界面磁电耦合和自旋电子输运的微观机制

项目名称： 铁磁/铁电异质外延结构的界面磁电耦合和自旋电子输运的微观机制

项目编号： No.51462019

项目类型： 地区科学基金项目

立项/批准年度： 2015

项目学科： 无机非金属材料学科

项目作者： 代建清

作者单位： 昆明理工大学

项目金额： 48万元

中文摘要： 复相多铁性材料可在室温下具有大的磁化和电极化强度以及强的磁电耦合效应，具有可预期的广阔应用前景。人工铁磁/铁电外延异质结构和多铁性隧道结是材料科学和凝聚态物理中的备受关注的新领域，其界面磁电耦合效应和自旋电子输运性质是非常值得研究的课题。 本项目拟利用密度泛函理论和量子弹道输运方法，对铁磁/铁电外延异质结构和多铁性隧道结进行界面电子结构、磁电耦合效应、及自旋电子输运等物理性质进行全方位的第一性原理计算研究。1）确定材料体系和界面结构对界面电子重构和磁电耦合机制的影响规律，阐明界面磁结构和磁相互作用类型对铁电磁性相互调控的物理机制，设计具有更强磁电耦合效应的人工铁磁/铁电超晶格；2）研究铁磁/铁电/铁磁多铁性隧道结中界面化学键合、铁电极化屏蔽机制、磁电耦合效应对自旋电子输运性质的影响规律，利用界面原子层的自旋阀效应，结合隧穿磁致电阻和隧穿电致电阻效应，探索具有实用前景的多态电阻存储器件。

中文关键词： 复相多铁性材料；第一性原理；磁电耦合机制；自旋电子输运

英文摘要： Multiferroic magnetoelectric composites have potential applications in novel multifunctional devices due to the coexistence of large ferromagnetism and ferroelectricity above room-temperature, as well as the strong coupling interaction between the two ferroic orders. The epitaxial ferromagnetic/ferroelectric (FM/FE) heterostructures have recently attracted considerable interest in the fields of materials science and condensed matters physics. In particular, the underling mechanisms for interfacial magnetoelectric coupling and spin-dependent tunneling deserve intensive investigations. In this proposal, based on the density functional theory and the quantum ballistic transport approaches, we prepare for performing first-principles calculations concerning interfacial electronic structure, magnetoelectric coupling, and spin-dependent transport for the epitaxial FM/FE heterostructures and FM/FE/FM multiferroic tunnel junctions. 1) We plan to determine the dependences of interfacial electronic reconstruction and magnetoelectric coupling mechanisms on the different materials systems and interface atomic configurations. In order to design FM/FE superlattices with more efficient magnetoelectric effects by combining different coupling mechanisms, we should also elucidate the influences of the interfacial magnetic structure and the type of magnetic interaction on the cross-coupling between magnetism and ferroelectricity. 2) For FM/FE/FM multiferroic tunnel junctions, we focus on the spin-dependent transport and the related tunneling magnetoresistance and electroresistance effects. With the purpose of obtaining insights into the underlying mechanisms, we have to illustrate the effects of interfacial chemical bonding, screening of ferroelectric polarization bound charges, and interfacial magnetoelectric coupling on the transmission distributions for each spin-channel. Utilizing the effect of atomic-scale spin-valve, we design novel four-state resistance devices based on FM/FE/FM multiferroic tunnel junctions by combining the tunneling magnetoresistance and electroresistance effects.

英文关键词： composite multiferroics;first-principles;magnetoelectric coupling;spin-dependent tunneling