基于BiFeO3的铁电/非铁电多层膜和超晶格研究

The aim of artificially designed heterostructure and supperlattice is to modulate the physical properties of parent phases by the heterojunction interfaces and the configuration of supperlattices, for obtaining enhanced functional properties and/or exotic quantum phenomena and functional behaviors. Many interesting physical behaviors, such as interface induced magnetoelectric coupling, two dimensional electron gas, metallic ferroelectric domain walls, and toplogical ferroelectric domains, etc, have been observed in perovskite oxide ferroelectric heterostructures and supperlattices. BiFeO3 (BFO) is a room-temperature multiferroic material with greatest potential for application in the areas of novel information storage, photovoltaic, and photocatalysis, etc，but there still are some weaknesses such as small magnetoelectric coefficient and large leakage to be improved. In this project, perovskite oxide multilayers and supperlattices based on BFO will be fabricated by laser molecular beam epitaxy, dielectric SrTiO3 and metallic SrRuO¬3 will be used as the another parent phase, respectively, for they have different valence state compared with BFO. It will be focused on studying the effects of interface polarization discontinuity and charge mismatch on the physical behaviors of ferroelectric polarization, two dimensional metallic domain wall or interface, magnetoelectric coupling, etc. The aim of this project is to modulate the domain configuration and functional properties of BFO multilayers and supperlattices by artificial interface, to explore exotic physical phenomena and mechanisms for acquiring new supperlattice materials with enhanced functional properties.

人工设计异质结和超晶格的目的是通过异质界面和超晶格结构来调控母相材料的物理特性，获得具有增强的或者母相材料所不具有的新奇量子现象和功能特性。在钙钛矿氧化物铁电异质结和超晶格中已经观察到许多有趣的物理现象，如由异质界面诱发的磁电耦合、二维电子气、铁电拓扑畴结构等。BiFeO3(BFO)是引人注目的室温多铁性材料，在新型信息存储、传感器、光电和光催化等领域有着重要的应用前景，但是依然存在磁电耦合系数小和漏电等亟待解决的问题。本项目选择BFO以及与其有不同价态类型的介电材料SrTiO3或导电材料SrRuO3为母相材料，用激光分子束外延技术分别生长具有界面极化不连续和电荷失配等特性的异质多层和超晶格结构，研究界面和超晶格结构对铁电极化、二维畴壁导电、磁电耦合等物理特性的影响，目标是通过人工界面实现对BFO多层膜和超晶格的电畴结构和功能特性的调制，获得具有增强功能特性的薄膜材料。

人工设计异质结和超晶格的目的是通过异质界面和超晶格结构来调控母相材料的物理特性，获得具有增强的或者母相材料所不具有的新奇量子现象和功能特性。在钙钛矿氧化物铁电异质结和超晶格中已经观察到许多有趣的物理现象，如由异质界面诱发的磁电耦合、二维电子气、铁电拓扑畴结构等。BiFeO3(BFO)是引人注目的室温多铁性材料，在新型信息存储、传感器、光电和光催化等领域有着重要的应用前景。本项目选择BFO以及与其有不同价态类型的介电材料SrTiO3或导电材料SrRuO3为母相材料，用激光分子束外延技术分别生长多种BFO外延薄膜及质多层和超晶格结构，研究了化学配比、机械应力、掺杂等因素对BFO薄膜物性的影响，观察到BFO/SRO多层膜中铁电近邻效应和反常霍尔效应等，并界面终结层控制多层膜中铁电极化方向，实现极化‘头对头’和‘尾对尾’的畴结构。