Student Abstracts: Materials Sciences at BNL

Evolution of Microstructure and Magnetic Structure of Epitaxial CoPt L10 Films. KAREEN RIVIERE (Brown University, Providence, RI 02912) DR. LAURA H. LEWIS (Brookhaven National Laboratory, Upton, NY 11973) .
CoPt films are under consideration as the next-generation high-density magnetic recording media. To evaluate the suitability of this material, the microstructure and magnetic domain configurations of crystallographically ordered (L1o-type) CoPt thin films of 50 nm thicknesses were characterized using atomic force microscopy (AFM) and magnetic force microscopy (MFM). These CoPt films were epitaxially grown at Carnegie Mellon University by low-rate DC sputtering on MgO substrates that were heated during deposition at temperatures ranging from 400 °C-750 °C. AFM images demonstrated that grain size and the tendency to grain cluster increased with increasing substrate temperature. The magnetic domain attributes progressed from long maze-like domains to concentric fingerprint-like domains and then changed to discontinuous domains with increased substrate heating temperature. The evolution of the microstructure and magnetic domain character is attributed to the thermal energy available to the film during growth. The results indicate that the microstructure and magnetic domain structure are most uniform and continuous at intermediate substrate temperatures.