Magnetic and Morphological Properties of Electrodeposited Thick FePt Films on Metallic (Au, Ag, Cu) Underlayers
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O R I G I N A L PA P E R
Magnetic and Morphological Properties of Electrodeposited Thick FePt Films on Metallic (Au, Ag, Cu) Underlayers S. Thongmee · I. Ming Tang
Received: 19 January 2013 / Accepted: 25 February 2013 © Springer Science+Business Media New York 2013
Abstract Electrodeposited thick films of FePt (with the nominal composition 50 % Fe/50 % Pt) on three metallic (Au, Ag, Au) underlayers were annealed at various temperatures. The magnetic and morphological properties of the resulting films were then monitored. The Au and Ag underlayers promoted the growth of the (bct) L10 FePt phase. The greater growth of this phase in the films deposited on the Ag underlayer led to the crystallographic texturing in the (001) direction. This was accompanied by a significant magnetic anisotropy and a negative shift of the remanent magnetization in the presence of an applied field. The coercivity of the Ag underlayer films increased to 18 kOe while the coercivity of the Au underlayer films decreased to ∼2 kOe when the annealing temperature was increased to 800 ◦ C. Keywords FePt film · Au, Ag and Cu underlayer · High coercivity · Magnetic texture · Remanent magnetization
1 Introduction Ever since the discovery of giant magnetoresistance (GMR) by Fert and his co-workers [1] and by Grünberg and his co-workers [2] in the late 1980s, much interest has been S. Thongmee () Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand e-mail: [email protected] S. Thongmee · I.M. Tang Department of Material Science, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand S. Thongmee · I.M. Tang ThEP, Commission of Higher Education, 328 Si Ayuthaya Rd., Bangkok 10400, Thailand
shown in multilayer structures composed of alternating layers of ferromagnetic and non-ferromagnetic metals. The GMR phenomenon arises from the reorientation of a singledomain magnetic layer by an applied field. The need for single magnetic domains requires the magnetic layers to be thin. In the original studies, the alternating layers were Fe and Cr. Much research has been done since to find new combinations of magnetic and nonmagnetic materials [3]. FePt has attracted much attention due to its excellent magnetic properties such as large saturation magnetization and high magnetocrystalline anisotropy [4]. Much research has been carried out to develop hard magnetic films of this material because of its potential application in high-density recording media [5] and in micro-electro–mechanical systems (MEMS) [6]. The latter applications often require highcoercivity thick magnetic films. FePt films are mainly fabricated using physical vapor deposition (PVD) technique [7]. This technique is mainly used to fabricate small thickness films. Electroplating is a convenient and economical method for fabricating thick metallic films. FePt films have been prepared by electroplating using Cu as the underlayer [8, 9]. No crystallographic texture and magnetic anisotropy were seen in the FePt films deposited on Cu underlayers. One of
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