Physics and Astronomy, Department of

 

Date of this Version

12-2013

Citation

T. A. George, Magnetic Anisotropy and Exchange in (001) Textured FePt-based Nanostructures, PhD diss., Department of Physics and Astronomy, University of Nebraska-Lincoln, 2013.

Comments

A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Physics and Astronomy, Under the Supervision of Professor David J. Sellmyer. Lincoln, Nebraska: December, 2013

Copyright (c) 2013 Tom Ainsley George

Abstract

Hard-magnetic L10 phase FePt has been demonstrated as a promising candidate for future nanomagnetic applications, especially magnetic recording at areal densities approaching 10 Tb/in2. Realization of FePt’s potential in recording media requires control of grain size and intergranular exchange interactions in films with high degrees of L10 order and (001) crystalline texture, including high perpendicular magnetic anisotropy. Furthermore, a write-assist mechanism must be employed to overcome the high coercivity of L10 FePt nanograins. The research described in this dissertation examines potential solutions to the aforementioned problems. Specifically, a nonepitaxial method of fabricating highly (001) textured thin films is investigated by careful tuning of the as-deposited structure. Such highly textured films could be useful as a template for bit-patterned media. Secondly, control of grain size and intergranular magnetic interactions is demonstrated using non-magnetic additions of Al2O3, C, and Au. Finally, large reductions in the coercivity of high anisotropy, epitaxially grown L10 FePt islands are achieved in an exchange-coupled composite system by adding an exchange coupled layer of FePt:SiO2 with moderate anisotropy. The results show promise for the implementation of L10 FePt in future magnetic recording media and other nanomagnetic applications.