FRG: Atomic Design of Artificial Spinel Ferrites

锰铁氧体（MnFe 2 O 4）是一种混合尖晶石，其中当通过常规生长技术制备时，平均20%的Mn 2+离子驻留在B位点（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Mn 2+离子在B位点上的百分比。人工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MnFe 2 O 4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MnFe 2 O 4有很大不同。在这个计划中，我们的目标是探索影响给定组成的尖晶石结构的磁离子分布的能力，以制备（1）具有增强的饱和磁化强度的人工铁氧体和（2）设计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。我们的生长技术在以下意义上标志着与制备尖晶石铁氧体的传统或常规程序的重大偏离。通过我们开发的生长技术，现在可以人工控制尖晶石铁氧体晶胞内磁性离子的分布。这意味着改进的磁传感器，更小和有效的微波和电子设备的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.