CAREER: Microstructure and Mean Stress Evolution in Atomistic Ordering Thin Films

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TECHNICAL: With an ever-increasing demand for developing nanoscale devices, several significant challenges exist in 'scaling-down' intermetallics while maintaining their atomic-order stability. This is of particular interest to the magnetic storage industry, which needs new materials to achieve ultra-high storage density in the terabit per square-inch range. High magnetocrystalline anisotropy alloys FePt, CoPt, FePd and MnAl are candidate intermetallic compounds for the next-generation of magnetic data storage systems. When these metals are sputtered deposited as a nanogranular microstructure, they adopt a metastable phase requiring a high temperature anneal to form the appropriate chemically ordered phase. Stress can have a significant influence on the phase and microstructure at the nanoscale. The lack of sufficient atomistic microstructural characterization at the nanoscale has made this phase transformation not well understood. Research will provide the influence of residual stress on the nucleation and structural stability of ordered alloys in the nanometer regime. Atom Probe Tomography (APT), high-resolution transmission electron microscopy, and in-situ thin film stress monitoring will be coupled to address the effect of film stress on the early stages of ordering, composition segregation, and film growth. By correlating the residual stress state of a film to its microstructure and ordered phase evolution, the intermetallic stability relationship to size will be realized. NON-TECHNICAL: Results will have a major impact on the practical aspects of magnetic information storage. The research will balance teaching, scholarship, and service to the university and the scientific community. A synergistic program for the professional development and recruitment of graduate, undergraduate, and high school students into materials science and engineering will be developed. It will include a high school summer research experience, and teaching materials science to faculty from historically black colleges and universities (HBCU). A summer research sabbatical for HBCU faculty will be incorporated into the research. Research will be disseminated to the magnetic industry through workshops coordinated by the Center for Materials for Information Technology (MINT) at University of Alabama.