多铁性逆磁电效应异质结薄膜的制备与性能研究

Characters)：Recently, many attentions and researches are attracted on magnetoelectric composite thin films due to its multifunctional composite properties (the coexist of magnetic and electric and the ME coupling of the two orders). With the development of modern information functional devices, the needs of multifunction, miniaturization, low-power dissipation and eco-friendly materials are becoming more and more intensive. So preparing the 2-2 type converse magnetoelectric(CME) or electric controlled magnetization heterojunction composite thin films with high quality and excellent properties, studying the coupling mechanism and the electrical and magnetic propertis and further exploring the potential applications becomes the hot topic of multiferroic research. The main research object of this project is to explore a set of optimum BatiO3 epitaxy technique by pulse laser deposition method (PLD), obtain the high quality BTO films and further grow another layer of NiFe magnetic alloy thin films on it by magnetron sputtering technology (MS) to prepare eco-friendly electric controlling magnetization composite thin films. Then the growth processes/parameters, growth mechanism, microstructure, film thickness of each layer, strain conditions, lattice constant changing and the affects on thin film properties will be studied systematically and thoroughly. And at the same time the test and characterization method of electric controlling magnetization or CME coupling effect based on PPMS(Comprehensive physical properties measuring system) and MOKE (magneto-optic Kerr effect) platform will be investigated. At last, the theoretical model and prototype applications of CME effect of layer composite thin films in information storage and processing technology will be designed.

近年来，磁电复合薄膜因其具有优良的多功能复合特性而受到人们广泛的关注，成为多铁性领域新的重要研究热点。现代信息技术对功能器件在多功能化、微型化、低功耗和环境友好等方面的要求越发突出，制备性能优良的2-2型多层结构的逆磁电效应（即电控磁）复合薄膜，纳米尺度上研究其磁电耦合机理及性能，具有重要的学术价值和现实意义。本项目的主要目标是采用脉冲激光沉积法（PLD）生长高质量的BaTiO3外延薄膜，然后采用磁控溅射法（MS）在BaTiO3薄膜上生长镍铁基磁性合金层，制备出环境友好的NiFe/BaTiO3多层复合薄膜系列，研究其生长工艺、微结构、薄膜厚度、应力情况、晶格参数等对薄膜逆磁电复合性能的影响，进一步探索完善基于PPMS（综合物性测量系统）和MOKE（磁光克尔效应）测试平台研究逆磁电效应“电控磁”性能的表征方法，探索逆磁电效应在信息存储和处理技术上的可能应用，探索设计逆磁电效应应用的原型器件。

目前，器件发展的多功能化、小型化趋势和现代薄膜制备技术的快速发展，进一步凸显了“电控磁”磁电复合薄膜在电可调谐的未来薄膜器件领域的潜在应用。本项目旨在探索逆磁电效应材料体系、薄膜制备、结构表征和性能关系。以铁磁/铁电双层或多层纳米薄膜的制备为主线，重点针对磁电复合薄膜制备、性能调控和测试方法等工作中若干基础问题开展研究，预期制备出性能稳定的磁电复合薄膜，探索研究“磁控电”及“电控磁”性能的影响规律。选用环境友好型材料BaTiO3作为铁电材料，选用具有更小饱和场和矫顽场的NiFe合金作为铁磁材料。优化BaTiO3薄膜和NiFe薄膜的生长工艺，获得铁电性能更好、磁性更强以及磁电复合薄膜。选取BFCO和BFCNT制备多铁性氧化物异质结薄膜，研究多铁性材料磁电耦合的微观机理。通过生长取向的选择获得了铁电性能更好的单晶薄膜，通过对界面的热处理，实现了铁电性能的增强，通过铁磁/铁电的耦合，获得了耦合性能更好的磁电复合薄膜。针对异质结磁电薄膜体系，研究了磁电耦合的微观机理，为进一步在宏观和微观尺度上定性研究多铁磁电耦合效应提供参考。对于铋层钙钛矿体系，通过过渡金属和镧系离子的掺杂，实现了铁电、铁磁及磁电性能的增强。基于该项目所取得的成果为铁电存储区、储能器、光电器件、红外探测器以及磁电器件的制备提供了基础并创造了有利条件。