吸附氧与本征空位缺陷对BaTiO3薄膜磁性的协同作用机理研究

Perovskite oxides become a research hotspot because they have intensively potential applications in the microelectronics IC and magnetic storage due to its stable crystal structure and unique electromagnetic properties. However, the origin of d0 ferromagnetism observed in these perovskite materials is still unclear. The cooperative effect of adsorbed oxygen and the intrinsic vacancies are not considered in current magnetic analysis by experiments and theories, and the influence of intrinsic vacancy type on the concentration of adsorbed oxygen is not explored. To solve these problems, the project takes BaTiO3 as the object of research. By pulsed laser deposition technique, controllable fabrication of defected BaTiO3 with different concentration of adsorbed oxygen is achieved through the preparation of ceramic target with different ratio of chemical elements and the adjustment of oxygen pressure during preparation process. Combining the experimental and theoretical researches, the mechanism for the effect of intrinsic vacancy type on concentration of adsorbed oxygen and the cooperative effect of intrinsic vacancy and adsorbed oxygen on the magnetism will be investigated. This project will clarify the origin of ferromagnetism in undoped perovskite oxides, and provides new ideas and approaches for the design and the fabrication of new ferromagnetic materials.

钙钛矿型氧化物具有稳定的晶体结构与独特的电磁性能，在微电子集成电路与磁存储等领域存在巨大的应用前景，是一种性能优异用途广泛的新型功能材料。针对其d0铁磁性来源在实验和理论方面存在的分歧，现有研究未考虑吸附氧与本征空位的协同作用对材料磁性的影响，本项目以BaTiO3为研究对象，采用脉冲激光沉积技术，通过控制靶材中的化学元素计量比与沉积过程中的氧分压，制备出含不同空位类型的BaTiO3缺陷薄膜；利用程序升温脱附法脱附表面吸附氧后，通过控制再吸附过程中氧气压强的大小，获得吸附氧浓度不同的各缺陷态薄膜样品。利用原子力显微镜、场发射扫描电镜、X光电子能谱及超导量子干涉仪等测量手段，结合第一性原理计算研究BaTiO3薄膜中缺陷类型对吸附氧浓度的影响及二者的协同作用对薄膜磁性的影响，明确薄膜的缺陷类型、吸附氧浓度与磁性质的关系，阐明钙钛矿氧化物d0铁磁性的来源，为单相室温铁磁材料的设计和制备提供新思路。

针对BaTiO3 d0铁磁性来源在实验和理论方面存在的分歧，现有研究未考虑吸附氧与本征空位的协同作用对材料磁性的影响。项目利用脉冲激光沉积技术制备BaTiO3 薄膜，通过控制靶材中的化学元素计量比与沉积过程中的氧分压，制备了含不同缺陷类型的BaTiO3 薄膜。通过控制氧氛围，获得吸附氧浓度不同的BaTiO3 缺陷薄膜。研究了缺陷类型对表面吸附氧的影响及二者的协同作用对薄膜磁性的影响。实验表征结合理论分析探讨了BaTiO3 薄膜中缺陷类型对吸附氧浓度的影响机制及吸附氧与本征空位缺陷协同作用对薄膜磁性的影响机制，阐明无掺杂钙钛矿氧化物的铁磁性来源。项目执行过程中，项目组成员经过反复的实验试制，制备出吸附氧浓度不同的BaTiO3 缺陷薄膜，制备条件属于本项目的关键数据。BaTiO3 是一种典型的钙钛矿材料。由于其具有很多优良的特性，因此应用广泛。通过引入磁性，有望满足其在应用方面更多的需求。本项目的开展为单相室温铁磁材料的设计和制备提供了新思路。