Title

Thickness dependence of structure and magnetic properties of annealed Fe/Pt (n) multilayer films

Authors

Authors

B. Yao;K. R. Coffey

Abbreviated Journal Title

J. Appl. Phys.

Keywords

THIN-FILMS; FE/PT MULTILAYERS; GRAIN-GROWTH; FE-PT; TEMPERATURE; COERCIVITY; PHASE; COPT; Physics, Applied

Abstract

The L1(0) FePt phase material has potential applications for magnetic recording and permanent magnets due to its high magnetocrystalline anisotropy energy density. The heat treatment of [Fe/Pt](n) multilayer films is one approach to form the L1(0) FePt phase at a lower processing temperature, which is highly desirable for its applications. This paper reports the influence of film total thickness (8-100 nm) on the structure and magnetic properties of annealed [Fe/Pt](n) multilayer films. A novel technique based on hollow cone dark field transmission electron microscopy is used to determine the L1(0) phase fraction and grain size in the annealed films. It was found that the L1(0) phase fraction and grain size, ordering, and magnetic properties are strongly dependent on the total film thicknesses. An L1(0) FePt phase fraction close to 100% is achieved for a thick [Fe/Pt](n) multilayer film (100 nm) annealed at 400 degrees C for 1 h, while a value of only 36% is achieved for a thin film (8 nm) annealed at the same condition. In this work the L1(0) FePt phase nucleation density is also presented. These results suggest that the L1(0) phase formation is nucleation limited, and that the subsequent growth of L1(0) phase grains also strongly influences the structure and magnetic properties of the annealed films. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3073842]

Journal Title

Journal of Applied Physics

Volume

105

Issue/Number

7

Publication Date

1-1-2009

Document Type

Article; Proceedings Paper

Language

English

First Page

3

WOS Identifier

WOS:000266633500202

ISSN

0021-8979

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