Permanent-Magnet Properties of Thermally Processed FePt and FePt–Fe Multilayer Films

Authors

• Jian Zhou, University of Nebraska - Lincoln
• Ralph Skomski, University of Nebraska-LincolnFollow
• XINGZHONG LI, Nebraska Center for Materials and NanoscienceFollow
• Wei Tang, Department of Physics and Astronomy, University of Delaware, Newark, DE
• George C. Hadjipanayis, University of DelawareFollow
• David J. Sellmyer, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

9-1-2002

Comments

Published by IEEE; IEEE-Trans. Mag. 38, No. 5, 2802-2804 (2002). ©2002 IEEE. Permission to use. http://ieeexplore.ieee.org/

Abstract

FePt single-layer and FePt–Fe multilayer thin films are prepared by magnetron sputtering. By varying the Pt content, FePt, Fe₃Pt, or a mixture of FePt and Fe₃Pt can be obtained in Fe–Pt single layers. In annealed FePt–Fe multilayers, the coercivities decrease with the introduction of Fe layers compared to FePt single layers, while the magnetization increases. The single-phase behavior of the hysteresis loops of FePt–Fe multilayers indicates the existence of exchange coupling in these materials. For one FePt–Fe sample with optimized exchange coupling, the intrinsic properties correspond to an energy product of 19 MGOe. The texture of the magnets is determined by the (111) orientation of the crystallites. This means that the easy magnetization directions of the FePt grains form an angle of 54.7 with the film normal, but are randomly oriented in the film plane. It is analyzed how this easy-axis distribution affects the magnetic hysteresis.