FRG: Atomic Design of Artificial Spinel Ferrites

锰铁素体（MnFe2O4）是一种混合尖晶石，其中平均20%的Mn2+离子位于B位（八面体亚晶格）上。最近，我们设计了一种生长方案，通过该方案可以人为地控制B位上Mn2+离子的百分比。人造铁氧体薄膜的晶格常数和化学成分与块状尖晶石铁氧体或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块状MnFe2O4有很大不同。在这一提议中，我们的目的是探索影响给定成分尖晶石结构的磁性离子分布的能力，以制备(1)具有增强饱和磁化强度的人工铁氧体；(2)设计一种系统的方法来设计铁磁性尖晶石铁氧体。磁性和/或铁氧体材料的基础研究一直在下降，尽管世界市场严重依赖铁氧体材料。我们相信我们的研究将对铁氧体界和整个科学界产生广泛的影响。在以下意义上，我们的生长技术标志着与传统或常规尖晶石铁素体制备方法的重大背离。尖晶石铁氧体单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人工控制。这意味着改进磁传感器，更小、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.