Exchange Bias of Ideal Antiferromagnetic Thin Films

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The proposed research will focus on the study of exchange bias, a phenomenon resulting from the interface magnetic interactions between ferromagnetic and antiferromagnetic materials. Recent studies have established that the amount of interface disorder, defects in the antiferromagnet, the stoichiometry of the interface layer, and magnetic anisotropy energies influence the exchange bias, but the relative importance of these factors is not well understood. The main scientific objective of this proposal is to understand the effect of these parameters in well-characterized, ideal antiferromagnetic insulators, in order to eventually apply some of the ideas gleaned from these measurements to more complex antiferromagnets. Because the experiments will be carried out on relatively simple magnetic systems, the results will provide experimental data that could be explained using first principle models and simulated with a computer. In addition to the usual involvement of undergraduate and graduate students and postdocs, in the day-to-day research, there are three important educational activities associated with the proposed work: 1) involvement with science programs in middle schools in rural West Virginia; 2) development of interactive teaching tools for beginning physics lecture classes, and 3) development of new teaching materials for advanced laboratory. This program will have a significant impact on education from the 7-16 level and beyond, emphasizing science education for disadvantaged students in rural schools in West Virginia. This is especially important for the state of West Virginia, whose economy has traditionally relied on manufacturing and coal production, but where high-technology industry is increasingly playing an important role. Ferromagnetic materials are the basis of modern data storage devices, including computer hard disk drives. Modern magnetic sensors and proposed magnetic memory devices also rely on antiferromagnetic materials that can prevent ferromagnetic thin films from changing their magnetic properties when an external magnetic field is applied. The mechanism whereby this ferromagnetic-antiferromagnetic interaction occurs, called exchange bias, is not well understood. One of the problems is that many antiferromagnetic materials have very complex magnetic configurations which make the scientific data difficult to analyze. The main scientific objective of this proposal is to understand the effect by using well-characterized, ideal antiferromagnetic thin film materials whose properties are relatively simple and well understood. Because of the simplicity of these materials, the results will provide experimental data that could be explained using first principle models and simulated with a computer. The ideas gleaned from these studies will be applied to the more complex antiferromagnets used in magnetic electronic devices. The long-term result will be magnetic electronic devices with increased storage capacity, lower power consumption, and increased speed. In addition to the usual involvement of undergraduate and graduate students and postdocs, in the day-to-day research, there are three important educational activities associated with the proposed work: 1) involvement with science programs in middle schools in rural West Virginia; 2) development of interactive teaching tools for beginning physics lecture classes, and 3) development of new teaching materials for advanced laboratory. This program will have a significant impact on education from the 7-16 level and beyond, emphasizing science education for disadvantaged students in rural schools in West Virginia. This is especially important for the state of West Virginia, whose economy has traditionally relied on manufacturing and coal production, but where high-technology industry is increasingly playing an important role.