正铁氧体和正交锰氧化物单晶膜中反铁畸变晶格的外延应变调控及室温磁电效应探索

项目名称： 正铁氧体和正交锰氧化物单晶膜中反铁畸变晶格的外延应变调控及室温磁电效应探索

项目编号： No.11274287

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： 吴文彬

作者单位： 中国科学技术大学

项目金额： 93万元

中文摘要： 具有典型Pbnm正交结构的稀土正铁氧体RFeO3是一类有趣的功能材料，显示高温（620-740 K）反铁磁序、强磁晶各向异性和自旋转向转变，且与其共角FeO6八面体的倾斜和旋转所导致的反铁畸变晶格不稳定性密切相关。近期研究表明八面体的倾、转自由度还与铁电序共存，一方面可导致如PbTiO3/SrTiO3界面处非正常铁电性的产生，另一方面在CaMnO3中反铁畸变的凝聚使其本征的正常铁电序淬灭，而若施加外延应变增强MnO6八面体的铁电畸变可诱发体系中显著的磁电耦合效应。因此，选择具有高温磁有序和正交反铁畸变的过渡金属氧化物薄膜进行研究，有望发现室温磁电效应；同时开展低对称性材料的共格生长及外延应变调控也是构筑和研究新奇氧化物界面的必要前提。本项目以正铁氧体及若干正交锰氧化物的外延生长为主干，重点探究应变调控对反铁畸变构型及其异质界面耦合和多铁序的影响规律，为氧化物电子学的进一步发展提供实验基础。

中文关键词： 氧八面体正交畸变；过渡金属氧化物薄膜；异质外延；界面八面体近邻效应；

英文摘要： After decades of research, transition-metal perovskite oxides, more than ever, seem destined for a great future. The interest in these oxides arises from the fact that they are based on the same simple perovskite structure and can exhibit a wide diversity of behaviors. Large and tunable dielectric constants, piezoelectricity, ferroelectricity, colossal magnetoresistance, charge-orbital ordering, magnetism, and superconductivity are examples of their most common properties, many of which are exploited in various technological applications. And recently, thanks to advances in deposition techniques, the interest in perovskite oxides moves greatly to films, multilayers and superlattices. The functional properties of ABO3 compounds are strongly sensitive to external parameters and it was shown that the engineering of epitaxial strain is a powerful tool that can be used to tune ferroelectricity or induce ferromagnetism in these systems. Going further and stacking different perovskites in epitaxial structures not only allows their properties to be combined but, sometimes, also totally new phenomena to be induced. The examples include the metallic interface found at the boundary between the insulators LaAlO3 and SrTiO3, and the emergence of improper ferroelectricity in ultrashort period PbTiO3/SrTiO3 superlattices. And

英文关键词： oxygen octahedral distortion；transition metal oxide films；heteroepitaxy；interfacial octahedral proximity；