双钙钛矿型室温磁电多铁性薄膜的制备和研究

项目名称： 双钙钛矿型室温磁电多铁性薄膜的制备和研究

项目编号： No.50802011

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 电工技术

项目作者： 白飞明

作者单位： 电子科技大学

项目金额： 20万元

中文摘要： 磁电多铁性材料是一类集磁性、铁电性于一体的多功能材料，在弱磁场传感器，磁电换能器及下一代磁数据存储器等方面具有十分广阔的应用前景。同时具备室温以上铁磁性、铁电性及较强磁电耦合效应的单相多铁性材料是目前国际上的一个研究热点和难点。理论上讲，双钙钛结构Bi2FeCrO6满足铁电性和铁磁性共存的晶格条件和自旋条件，并且有可能具备较强的磁电耦合效应，是一种有潜力的磁电多铁性材料。在本项目中，一方面我们用高压烧结法制备了纯相的Bi2FeCrO6，Ti和La掺杂的Bi2FeCrO6，并研究比较了其铁电和铁磁性能；另一方面用脉冲激光溅射法制备外延取向的Bi2FeCrO6薄膜，并在薄膜结构和性能的关系方面展开了研究；最后，为了克服测试薄膜磁电耦合系数的困难，我们利用扫描探针显微镜可以原位加电场观察局部微磁/电畴的变化的优势，发展了相应的磁电显微技术，并根据施加电场前后磁衬度相位信息重构了磁矩的变化，进而估算了磁电薄膜样品的磁电耦合系数。

中文关键词： 多铁性材料;磁电效应;双钙钛矿

英文摘要： Due to the spontaneous magnetization and polarization, multiferroic magnetoelectric materials have great potentials in applications such as weak magnetic field sensors, magnetoelectric transformers and magnetic data storage devices, etc. However, single-phase multiferroic materials with simultaneous ferromagnetism, ferroelectricity and strong magnetoelectric coupling above room temperature are still absent. Theoretically, double-perovskite Bi2FeCrO6 satisfies the requirement of both lattice structure and spin order for simultaneous ferromagnetism and ferroelectricity. In current work, on one hand, we have prepared phase pure Bi2FeCrO6, and Ti- and La-doped Bi2FeCrO6 ceramics by high pressure synthesis, and the magnetic and ferroelectric properties have been investigated. On the other hand, we have also grown epitaxial Bi2FeCrO6 thin films by pulsed laser deposition, and the relationships between phase structure, magnetic domain, piezoelectric domain and properties have been studied in details. Finally, in consideration of the difficulty in measuring the magnetoelectric coupling coefficient of thin film, we have developed a magnetoeletric microscopy method based on scanning probe microscopy. The magnetic domain contrast before and after applying electrical field in-situ have been observed, from which the magnetization change was reconstructed and the magnetoelectric coupling coefficient was calculated.

英文关键词： Multferroic materials; Magnetoelectric coupling; double perovskite