Growth of binary Ni–Fe ﬁlms: Characterisations at low and high potential levels Hilal Kuru a,n , Hakan Kockar a,1 , Mursel Alper b,2 , Oznur Karaagac a,1 a Physics Department, Science & Literature Faculty, Balikesir Universitesi, Fen Edebiyat Fakultesi, Fizik Bolumu, Cagis Yerleskesi, 10145 Balikesir, Turkey b Physics Department, Science & Literature Faculty, Uludag Universitesi, Fen Edebiyat Fakultesi, Fizik Bolumu, Gorukle, 16059 Bursa, Turkey article info Article history: Received 14 January 2013 Received in revised form 28 August 2014 Available online 22 October 2014 Keywords: Ni–Fe ﬁlms Electrodeposition Anisotropic magnetoresistance Magnetic properties Structural analysis abstract Binary Ni–Fe ﬁlms relating their magnetoresistance and magnetic properties with crystal structure and surface morphology, and the corresponding ﬁlm composition were investigated at low and high de- position potentials. Based on the results obtained from a cyclic voltammetry curve, a potential region between 1.3 V and 1.8 V was selected, and the current–time transients were recorded to control the proper ﬁlm growth. The Ni–Fe ﬁlms were potentiostatically electrodeposited on polycrystalline titanium substrates at low ( 1.3 V) and high ( 1.8 V) deposition potential. The data from the energy dispersive X-ray spectrometry and the inductively coupled plasma atomic emission spectroscopy demonstrated that the Ni and Fe content in the ﬁlms varied as the potential changed. The magnetotransport properties and magnetic characteristics studied by a vibrating sample magnetometer (VSM) were observed to be af- fected by the deposition potentials. All ﬁlms were also noted to exhibit anisotropic magnetoresistance behaviour. At low potential, the magnitude of the longitudinal magnetoresistance (LMR) was high (3.93%) and that of the transverse magnetoresistance (TMR) was low (3.49%) while for the ﬁlm at high potential the LMR (2.76%) and the TMR (3.66%) magnitudes were obtained. Magnetization measurements by VSM revealed that the saturation magnetization, M s was 779 emu/cm 3 and saturation ﬁeld, H s was 142 Oe at low potential while for the ﬁlms deposited at high potential the M s and H s were 749 emu/cm 3 and 262 Oe, respectively. However, the coercivities in the ﬁlms were found to be around 4.5 Oe, re- gardless of the potential. Also, the magnetic easy axis was found to be in the ﬁlm plane for all samples. The structural analysis of the ﬁlms was carried out using the X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. To XRD analysis, all ﬁlms have a strong (111) texture of face- centred cubic structure and the lattice parameters, d-spacings and average grain size slightly changed with deposition potential. The ﬁlms studied by SEM revealed that they have smaller grains grown at low deposition potential compared to those deposited at high potential. The differences observed in the properties of the ﬁlms might be attributed to the compositional changes caused by the deposition po- tential. & Elsevier B.V. All rights reserved. 1. Introduction Up to now, various methods such as molecular beam epitaxy, sputtering and electrodeposition have been used for preparing the iron-group metals (Fe, Ni, Co) and binary alloy systems due to the numerous important industrial applications in computer read/ write heads and microelectromechanical systems (MEMS) [1–3]. The physical methods such as molecular beam epitaxy and sputtering are still largely used although they require ultra-high vacuum and consequently expensive [4,5]. However, electro- deposition is simpler, more ﬂexible and cheaper process available for the fabrication of single and multilayered ﬁlms than the va- cuum techniques [6–8]. In recent years, the magnetic properties sought in these group metals and binary alloy systems exhibit anisotropic magnetore- sistance (AMR) and also are high saturation magnetization and low coercive ﬁeld [8–14]. The Ni–Fe alloy is one of the most stu- died materials, which these interesting properties exists [15–17]. With these properties, Ni–Fe ﬁlms as the AMR sensors are ex- tensively used to detect the weak magnetic ﬁelds in recording heads of magnetic data storage systems such as hard disks [1,18,19]. Iron-group metals such as iron [20–24] and electro- deposited binary alloys [8–14,25–29] have been improved by Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jmmm Journal of Magnetism and Magnetic Materials http://dx.doi.org/10.1016/j.jmmm.2014.10.058 0304-8853/& Elsevier B.V. All rights reserved. n Corresponding author. Fax: þ90 266 612 12 15. E-mail addresses: htopcu@balikesir.edu.tr (H. Kuru), hkockar@balikesir.edu.tr (H. Kockar), malper@uludag.edu.tr (M. Alper), karaagac@balikesir.edu.tr (O. Karaagac). 1 Fax: þ90 266 612 12 15 2 Fax: þ90 224 294 18 99. Journal of Magnetism and Magnetic Materials 377 (2015) 59–64