Hysteresis of granular FePt:Ag films with perpendicular anisotropy

Author

Yan, M.L. ; Skomski, R. ; Kashyap, A. ; Gao, L. ; Liou, S.H. ; Sellmyer, D.J.

Author_Institution

Dept. of Phys., Univ. of Nebraska, Lincoln, NE, USA

Volume

40

Issue

4

fYear

2004

fDate

7/1/2004 12:00:00 AM

Firstpage

2495

Lastpage

2497

Abstract

Intergranular interactions in nanostructured FePt:Ag thin films and their effect on magnetic hysteresis are investigated. The films, produced by multilayer deposition plus rapid thermal annealing, consist of FePt nanoparticles embedded in a silver matrix. They are investigated by magnetization measurements and magnetic force microscopy. Analytical model calculations, supported by micromagnetic simulations, are used to elucidate the relation between coercivity, hysteresis-loop slope, and spatial correlations during magnetization reversal. The analytical calculations yield simple expressions for the loop slope and the coercivity as a function of the intergranular exchange. Small intergranular exchange enhances the coercivity, but for strong exchange there is a self-energy cutoff, associated with the onset of cooperative reversal and preventing alpha from becoming negative.

Keywords

exchange interactions (electron); magnetic force microscopy; magnetic particles; magnetic thin film devices; magnetisation reversal; micromagnetics; nanostructured materials; perpendicular magnetic anisotropy; rapid thermal annealing; FePt nanoparticles; FePt:Ag; analytical model calculations; coercivity enhancement; coercivity property; cooperative reversal; granular films; hysteresis-loop slope; intergranular exchange; intergranular interactions; loop slope; magnetic force microscopy; magnetic hysteresis; magnetic recording; magnetization measurements; magnetization reversal; micromagnetic simulations; multilayer deposition; nanostructured thin films; perpendicular anisotropy; rapid thermal annealing; self-energy cutoff; silver matrix; spatial correlations; Analytical models; Anisotropic magnetoresistance; Coercive force; Magnetic films; Magnetic hysteresis; Magnetic multilayers; Magnetization; Nanoparticles; Rapid thermal annealing; Silver; Anisotropy; magnetic recording; magnetization reversal;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2004.832168

Filename

1325549