| AVS 59th Annual International Symposium and Exhibition | |
| Thin Film | Wednesday Sessions |
| Session TF+MI-WeA |
| Session: | Thin Films for Memory and Data Storage |
| Presenter: | M.A. Steiner, University of Virginia |
| Authors: | M.A. Steiner, University of Virginia R.B. Comes, University of Virginia J.A. Floro, University of Virginia W.A. Soffa, University of Virginia J.M. Fitz-Gerald, University of Virginia |
| Correspondent: | Click to Email |
Thin films of 3d-4d/5d metallic alloys such as Fe-Pt, Co-Pt, and Fe-Pd are of technological interest due to their ordered L10 tetragonal phase which exhibits high magnetocrystalline anisotropy comparable to that of 3d-4f rare earth magnets. A combination of hard magnetic properties with ductility and corrosion resistance makes this family of alloys ideal for applications including micro-electro-mechanical systems and ultra-high-density magnetic storage. These alloys are known to develop unique microstructures, including a novel strain-induced chessboard eutectoid microstructure featuring exchange coupling effects that has been found between the hard L10 and soft L12 magnetic phases of the Co-Pt system. Within this class of materials, Fe-Pd alloys possess a somewhat lower magnetocrystalline anisotropy compared to Co-Pt and Fe-Pt, but the Fe-Pd phase diagram showing considerably lower order-disorder transition temperatures renders them well-suited for nanostructured magnetic applications and study.
Epitaxial films of Fe38.5Pd61.5 at the L12-L10 eutectoid composition have been grown on MgO 001 oriented substrates by pulsed laser deposition. These films exhibit atomic ordering with increasing temperature, transitioning from the disordered A1 (FCC) phase to the ordered L12 phase. Fe38.5Pd61.5 films grown at 550oC have been found to possess a two-phase microstructure of prismatic 50-100 nm disordered A1 secondary phases with 110 oriented facets embedded within an ordered L12 matrix. These secondary phases exhibit single domain magnetic axis rotation, while the easy magnetic axis of the ordered L12 matrix lies in plane due to strain induced by epitaxy. The growth these two-phase films has been studied as a function of deposition time. The films grown in this study were characterized by x-ray diffraction, vibrating sample magnetometry, atomic and magnetic force microscopy, and high resolution scanning electron microscopy.