| AVS 54th International Symposium | |
| Magnetic Interfaces and Nanostructures | Wednesday Sessions |
| Session MI-WeM |
| Session: | Magnetic Thin Films and Nanostructures |
| Presenter: | J.R. Skuza, The University of Toledo |
| Authors: | J.R. Skuza, The University of Toledo R.A. Lukaszew, The University of Toledo C. Clavero, Instituto de Microelectrónica de Madrid - IMM (CNM - CSIC), Spain D.A. Walko, Argonne National Laboratory R. Clarke, University of Michigan, Ann Arbor |
| Correspondent: | Click to Email |
The FePt binary alloy system exhibits several chemically ordered phases (i.e., L10 and L12) depending on the Fe:Pt stoichiometry. This chemical ordering affects the crystallographic structure of the alloy and hence the magnetic anisotropy. For example, in thin films of this alloy, the L10 phase exhibits strong perpendicular magnetic anisotropy when the ordering axis is in the growth direction (~107 erg/cc), while the L12 phase exhibits in-plane magnetic anisotropy. Thus, suitable combinations of these chemically ordered phases have been proposed for the next generation of magnetic recording media with tilted magnetization. A significant challenge for this latter application is to achieve chemically ordered nanostructures that can further push the present super-paramagnetic limit. Here, we report on our recent magnetic and real time thermal annealing studies of nanostructured FePt thin films. FePt nanocomposite thin films were obtained by implanting Fe+ ions into epitaxial Pt thin films using the Toledo Heavy Ion Accelerator (THIA). The size and penetration depth of the resulting Fe nanoclusters were tailored by modifying the implantation conditions (i.e., ion beam energy and implantation dose). Upon annealing these nanocomposite samples at the Advanced Photon Source at Argonne National Laboratory, we observe within minutes the onset of the L12 phase at ~400° C with further re-ordering and formation of the L10 phase at ~500° C. Further data analysis shows that the activation energy of the L10 phase in these nanocomposite samples is ~1.0 eV. Our magnetic measurements show a strong out-of-plane component of the magnetic anisotropy after the annealing treatment consistent with the formation of the L10 phase.
This work was partially supported by the National Science Foundation (DMR Grant #0355171), the American Chemical Society (PRF Grant #41319-AC), and the Research Corporation Cottrell Scholar Award. Use of the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The authors would like to acknowledge M. S. Brown for his assistance during ion implantation.