Nanoscale Segregation in Next-generation Hard-Drive Thin Films Gregory B. Thompson, University of Alabama, Tuscaloosa, DMR Intellectual Merit Research motivation: Hard drive storage capacity has been increasing at an exponential rate over the past decade. To continue this trend, a new class of thermally stable, hard-magnets will be required; FePt is a candidate next-generation media material. Unfortunately, FePt requires a high-temperature anneal to phase transform into the correct atomic structure required for high density storage applications. This anneal results in grain growth destroying the microstructure needed for high density bits. This research fundamentally addresses the link between grain growth and atomic ordering in the nanometer scale regime. Results: Though the FePt phase transformation is a simple polymorphic phase transformation (change in crystal structure and not composition), this research has provided experimental verification that, at the nanoscale, compositional fluctuations do exist and influence the phase transformation process and kinetics. Understanding this behavior will ultimately lead to a better understanding of how to control order and grain growth in nanometer sized intermetallics. Using a Local Electrode Atom Probe (LEAP), the program has provided 3D reconstructions of Fe and Pt atom maps and have been able to experimentally confirm modeling predictions of Pt segregation, seen in the figures provided. Research is underway to determine the evolution of the segregation as a function of time, temperature and ternary alloy additions. Pt atom map Iso-cocentration surfaces and compositional pipe grain boundaries, Pt enrichment

Utilizing Research for Educational Development This NSF CAREER grant has been leveraged with the NSF-DMR program “Introducing Materials Science and Engineering Curriculum to Historically Black Colleges and Universities (HBCU)” (DMR ). Subsequent summers, HBCU faculty can return to UA to conduct ‘summer research sabbaticals.’ In 2007, Prof. Naga Sundar (Chemistry) of West Virginia State University (WVSU) along with Jennifer Thompson, an REU from WVSU supported by this CAREER grant, worked with Prof. Thompson on atom probe studies of Fe(Cu)Pt thin films. By having both the professor and undergraduate student from the same institution at UA provided significant synergy in the research interaction and productivity with Prof. Thompson. Broader Impact Also, during the summer of 2007, Kristy Tippey, a Central High School student, and Hiram Purser, Hillcrest High, worked with Prof. Thompson on atom probe studies as part of the Nanoscience and Engineering Summer Research Internship, co-founded and directed by Prof. Thompson and Prof. Nikles (Chemistry). This 10-week internship, which involves faculty across department and college boundaries, allows local high school students the opportunity to perform cutting-edge research. Their projects eventually become the catalysis for entering science fairs and science scholarship competitions. But more importantly, the program provides a ‘hands-on’ experience of careers as scientists and engineers. The CAREER grant is currently supporting the PhD studies of Karen Torres, a Hispanic American female graduate student. Prof. Thompson and Ms. Torres have ample multi-disciplinary interaction in UA’s Center for Materials for Information Technology ( Kristy Tippey, a high school intern, ‘at the controls’ of UA’s Local Electrode Atom Probe (LEAP) Gregory B. Thompson, University of Alabama, Tuscaloosa, DMR