Magnetic properties of Ni 1xy Co x Fe y films deposited by polyol electroless process J.K. Vemagiri, S.K. Murthy, R.A. Gunasekaran * , P. Coane, K. Varahramyan Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA 71272, USA Received 23 February 2003; accepted 7 March 2003 Abstract Electroless deposition using a nonaqueous, polyol process is carried out to produce nickel-rich Ni 0.5 Co 0.5  x Fe x and cobalt- rich Co 0.5 Ni 0.5  x Fe x (x = 0, 0.1, 0.3, 0.5) ternary alloy films, and investigate the effect of incorporating iron on the morphology and magnetic properties of these two series of films. The plating solution used to deposit these films is prepared by mixing proportional volumes of equimolar metal salts suspended in ethylene glycol. Plating was performed by refluxing the nonaqueous solution at a temperature of 194 jC. The deposited films were characterized by electron microscopy, optical interferometry and X-ray diffraction. In the case of cobalt-rich films (Co 0.5 Ni 0.5  x Fe x , x = 0.0 – 0.5), a transition in the crystal structure from lower symmetric orthogonal to higher symmetric tetragonal or cubic structures was observed with increasing iron content. There was no such change for the nickel-rich films (Ni 0.5 Co 0.5  x Fe x, x = 0 – 0.5). The addition of iron was found to increase the surface roughness of both series of films. The magnetic measurements showed excellent soft-magnetic characteristics for as synthesized Co 0.5 Fe 0.1 Ni 0.4 film with M sz , H cz , M s? and H c? values of 725.2 emu/cm 3 , 28 Oe, 205 emu/g and 176.5 Oe, respectively. The incorporation of iron was found to enhance the soft-magnetic characteristics of the otherwise weak magnetic Ni 0.5 Co 0.5 film. D 2003 Elsevier Science B.V. All rights reserved. Keywords: Crystal structure; Electron microscopy; Magnetic materials; NiCoFe alloy; Polyol process; Thin films 1. Introduction Soft-magnetic materials and thin films exhibiting improved performance are being synthesized by sev- eral novel methods for different applications [1–32]. The polyol process, which has been traditionally used for the synthesis of powders, is now being employed for the preparation of films [30]. Many alloy materials such as Co – Ni, Ni – Fe, Co – B, Co – Fe – B, Co – Ni – P and Co – Ni – Fe are being developed for use in modern high density recording and data storage discs [1–24]. In the past, induction writing heads were used for writing bit information on the discs [25]. Recently, nanostructured soft-magnetic films that exhibit giant magnetoresistive (GMR) behavior have emerged as an important component in the thin film read/write heads [26]. Preparation of these soft-magnetic films was dem- onstrated in the nanostructured phase by the polyol method [27]. The reduction of grain size of material to nano-level has shown to produce unique properties, 0167-577X/03/$ - see front matter D 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0167-577X(03)00274-X * Corresponding author. Tel.: +1-318-257-5115; fax: +1-318- 257-5104. E-mail address: rag@coes.latech.edu (R.A. Gunasekaran). www.elsevier.com/locate/matlet Materials Letters 57 (2003) 4098 – 4107