FRG: Atomic Design of Artificial Spinel Ferrites

锰铁氧体(MnFe2O4)是一种混合尖晶石，用传统的生长方法制备时，其中平均有20%的Mn2+离子存在于B位(八面体亚晶格)上。最近，我们设计了一种生长方案，通过它可以人工控制B位上的Mn2+离子的百分比。人工合成的铁氧体薄膜的晶格常数和化学成分与尖晶石型铁氧体和MnFe2O4相同，但磁性能、交换常数、Neel温度、饱和磁化强度和磁各向异性场与典型的MnFe2O4块体有很大的不同。在这项计划中，我们的目标是探索特定组成的尖晶石结构对磁性离子分布的影响，以制备(1)增强饱和磁化强度的人造铁氧体和(2)设计一种系统的方法来设计铁磁性尖晶石铁氧体。尽管世界市场严重依赖铁氧体材料，但磁性和/或铁氧体材料的基础研究一直在下降。我们相信，我们的研究将对铁氧体社区和整个科学界产生广泛的影响。我们的生长技术标志着在制备尖晶石铁氧体方面与传统或传统工艺在以下方面的重大偏离。尖晶石铁氧体的晶胞内磁性离子的分布现在可以通过我们开发的生长技术来人工控制。这意味着改进的磁性传感器，更小和更高效的微波和电子设备，用于计算机和无线通信应用。

Manganese ferrite (MnFe2O4) is a mixed spinel in which on the average 20% of Mn2+ ions reside on the B sites (Octahedral sublattice), when prepared by conventional growth techniques. Recently, we have devised a growth scheme by which the percentage of the Mn2+ ions on the B sites can be artificially controlled. The lattice constant and chemical composition of the artificial ferrite films were the same as that a bulk spinel ferrite or MnFe2O4, but the magnetic properties, exchange constants, Neel temperature, saturation magnetization and magnetic anisotropy field were very different from that of a typical bulk MnFe2O4. In this proposal, our aim is to explore the ability to affect magnetic ion distributions of a spinel structure of given composition to prepare (1) artificial ferrites with enhanced saturation magnetization and (2) to devise a systematic approach to design ferromagnetic spinel ferrites.Fundamental research on magnetism and/or ferrite materials has been declining, although world markets depend heavily upon ferrite materials. We believe that our research will have a broad impact to the ferrite community and the scientific community at large. Our growth technique marks a significant departure from traditional or conventional procedures in preparing spinel ferrites in the following sense. The distribution of magnetic ions within a unit cell of a spinel ferrite can now be artificially controlled by growth techniques developed by us. This implies improved magnetic sensors, smaller and efficient microwave and electronic devices for computer and wireless communication applications.