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1. Influence of Film Thickness on the FeRh Magnetostructural TransitionLaura H. Lewis, Northeastern University, DMR 0908767 • Motivation: Understanding relationships between strain and dimension in multifunctional materials is of both basic scientific and technological interest. Model-system FeRhthin films show a heightened sensitivity to strain, not well understood, which modifies the inherent magnetostructural response. • Highlights from the project year: Epitaxial FeRh films were grown at varied thicknesses; 10-nm films exhibit a discontinuous structure (Fig. 1a, 1b) that also features an asymmetric and very broad magnetostructural transition as compared to thicker films (Fig. 1c). • Importance of results: The broadened cooling curve of the 10 nm film (Fig 1c) suggests that the discontinuous surface morphology leads to a ferromagnetic phase stabilization relative to that of the 50 nm FeRh film. Such a phase stabilization emphasizes the influence of surface-to-volume effects on the transition character and suggests that structural alterations may offer a means of tailoring the transition for technological applications such as media and sensor devices. (a) (b) (c) Fig. 1. Atomic force microscopy images demonstrating the change in surface morphology when the FeRh thickness is reduced from (a) 50 nm to (b) 10 nm. Changes to the surface morphology result in marked changes thermal response of the magnetic transition (c).

2. Influence of Film Thickness on the FeRh Magnetostructural TransitionLaura H. Lewis, Northeastern University, DMR 0908767 • This Materials World Network Project features a strong collaboration between Northeastern University, USA and the University of Leeds, UK. Particularly notable aspects include: • Nathan Mahlmeister (undergraduate student) was awarded the Northeastern University Presidential Global Scholarship to spend six months at the University of Leeds, in Dr. Christopher Marrow's laboratory, assisting in film deposition and preliminary characterization. • Melissa Loving (Ph.D. student) was provided with the opportunity to travel to the University of Leeds in Summer 2011 to assist in FeRh film deposition and preliminary characterization. • Collaborative experiments involving the use of large-scale scientific facilities (with participation from undergraduate & graduate students ) was carried out at: the National Synchrotron Light Source (USA) and Diamond Light Source Ltd. (UK). • Multiple presentations were made by the research team at the Intermag. & MMM research conferences. (top): Melissa Loving and Nathan Mahlmeister at the Diamond Light Source Ltd. (UK) (left): Melissa Loving and Felix-Jimenez-Villacorta (post-doctoral researcher) at the National Synchrotron Light Source (USA) The project has supported one graduate and two undergraduate students in the U.S. this year.