Mechanics, Materials Science & Engineering, May 2017
ISSN 2412-5954
Fabrication of Ni/Pd/Ni Multilayer by Pulsed Electrodeposition 13 T.A. Revathy1, T. Sivaranjani1, K. Dhanapal1, V. Narayanan2, A. Stephen1,a 1
Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai, Tamil Nadu, India
2
Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai, Tamil Nadu, India
a
stephen_arum@hotmail.com DOI 10.2412/mmse.99.96.980 provided by Seo4U.link
Keywords: multilayers, anisotropy, pulsed electrodeposition.
ABSTRACT. In the recent years, much interest has been aroused in ultrathin metallic layered magnetic structures. In particular, the sandwich of non-magnetic element between the magnetic elements is a key for the production of structures that exhibits magnetic anisotropy, it shows technologically significant application in perpendicular magnetic and magneto-optic recording. The pulsed electrodeposition method was employed for the deposition of pure nickel, nickel palladium (Ni/Pd) bilayer and nickel palladium nickel (Ni/Pd/Ni) trilayer films. Since pulsed electrodeposition is found to be a powerful tool for producing multilayers and alloys [1]. The X-ray diffraction pattern confirms the formation of fcc structure for both nickel and palladium. The cross sectional view of high resolution scanning electron microscopy shows the layer by layer deposition of nickel and palladium in Ni/Pd and Ni/Pd/Ni films. Vibrating sample magnetometer was employed to study the magnetic behavior of fabricated trilayer.
Introduction. Magnetic nanopattern multilayers establish a new refinement of materials unveiling a wide variety of application such as single electron device, optical media and high-density magnetic memory devices because of its unique property raised due to electron confinement produced in the interfaces of thin layers [2]. Nanopattern multilayered magnetic recording media provide adequate number of advantages than conventional continuous magnetic recording media, including better and higher recording density. Recently research has been made with various forms of magnetic nanopattern structures in order to attain the high recording density and multilayers with large magnetocrystalline anisotropy, high magnetization and chemical stability are found to be more suitable for these recording media [3]. Actually, the magnetic anisotropy of the elements are modified due to the hybridization effects and strain at the interfaces of multilayers comprising of ferromagnetic and non-ferromagnetic elements with periodic repetition[4]. Anisotropy of the film also depends upon the thickness of the layer. The structure, growth condition and layer composition profiles the magnetic property. Fabrication of layer by layer assembly of ferromagnetic nickel and nonferromagnetic palladium multilayers are done by several technique such as sputtering, evaporation, chemical vapor deposition, other vacuum deposition processes and electrodeposition. Among them Pulsed electrodeposition (PED) is the less expensive and simple method for depositing the films since PED has three parameter which can control the nature of the deposit like smoothness, film formation, crystallinity, etc., In this work, our aim has been to fabricate Ni, deposit pure nickel, nickel palladium (Ni/Pd) bilayer and nickel palladium nickel (Ni/Pd/Ni) trilayer so as to study the behaviour of nickel and palladium when they are in layered nature and reported the investigation of structural, morphological and magnetic properties of layered films. Experiment
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Mechanics, Materials Science & Engineering, May 2017
ISSN 2412-5954
Multilayer films were fabricated by pulsed electrodeposition method using the standard two electrode system. The stainless steel of grade 316L was used as cathode which is the working electrode while graphite sheet served as an anode. The electrodes were cleaned by conventional method. The area of the working electrode is 10 cm2. The electrolyte was prepared using double distilled water. The bath composition and experimental conditions are given in Table 1. The Ni/Pd and Ni/Pd/Ni layered film were deposited one by one from their respective electrolyte bath. Table 1. Bath and experimental condition of Pure Ni, Ni/Pd, Ni/Pd/Ni films. Bath composition
Applied current
Duration of deposition
Ton and Toff
pH
Nickel layer
0.5 M of NiSO4 0.1 M of boric acid
0.25A
20 min
2 ms and 9 ms
3
Palladium layer
0.05 M of Palladium acetate
0.2A
5 min
2 ms and 9 ms
3
After the deposition, the layered film was subjected to various characterization. The structural information were examined using X-ray diffraction (XRD), the formation of layered nature was observed by employing field emission scanning electron microscopy (FE-SEM) and magnetic behaviour was examined using vibrating sample magnetometer (VSM). Results and discussion XRD analysis The deposited films were investigated for structural information by XRD (GE-XRD 3003 TT) in standard Ni/Ag and Ni/Ag/Ni film are shown in Fig. 1.
The peaks at 40.150, 46.700 and 68.190 were attributed to the (111), (200) and (220) planes of fcc phase of Pd respectively and the peaks at 44.550, 551.890 and 76.450 were corresponds to the fcc MMSE Journal. Open Access www.mmse.xyz
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Mechanics, Materials Science & Engineering, May 2017
ISSN 2412-5954
planes of Ni (111), (200) and (220) respectively. In the case of Ni/Pd film, both palladium and nickel are in crystalline nature, which is confirmed by sharp intense peaks. On the other hand, intensity of nickel is decreased as palladium layer was coated over it. The intensity of Ni peaks was again increased in Ni/Ag/Ni film and palladium peak intensity decreased when compared to the Ni/Pd film. FE-SEM analysis The layered nature of the films were inspected by HRSEM. The cross sectional view of all the Ni, Ni/Pd, Ni/Pd/Ni were shown in Fig. 2. The cross sectional view of pure Ni film is shown in Fig. 2 (a) and found to be a smoo respectively. The thickness of the layers was calculated using ImageJ software. The cross sectional view of Ni/Pd/Ni was shown in Fig. 2 (c), the image revealed the formation of Ni/Pd/Ni trilayer film in such a way that the Pd layer is sandwiched in between the two Ni layers. In the trilayered film, Ni layer is found to be dominant with the
(a)
(b)
(c)
Fig. 2. (a) Cross sectional FESEM image of pure Ni film, (b) Cross sectional FESEM image of Ni/Pd film, (c) Cross sectional FESEM image of Ni/Pd/Ni film. Magnetic property analysis The magnetic behaviour of the deposisted films were examined using VSM (Lakeshore VSM 7410). The hysteresis behaviour of pure nickel, Ni/Pd and Ni/Pd/Ni films are shown in Fig. 3 MMSE Journal. Open Access www.mmse.xyz
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Mechanics, Materials Science & Engineering, May 2017
ISSN 2412-5954
Fig. 3. Hysteresis behaviour of The saturation magnetization values of Pure Ni, Ni/Pd and Ni/Pd/Ni is foung to be 104.60 emu/cm2, 26.1 emu/cm2 and 137.2 emu/cm2 respectively. value decreases for Ni/Pd layer when compared to pure nickel which is because of non-ferromagnetic palladium. The increase in saturation magnetization for Ni/Pd/Ni layer compared to Ni/Pd layer is due to the presence of third layer nickel. The loop reveals that the coercivity value for all the three films are almost same, which indicates that the magnetic field required for demagnetization, is same for all the films. Summary. The pure Ni, Ni/Pd and Ni/Pd/Ni films were deposited fabricated by simple pulsed electrodeposition method. The XRD pattern unveils the formation of fcc structure for both palladium and nickel in Pure Ni and layered films. The layered nature of Ni/Pd, Ni/Pd/Ni and film nature of pure Ni were determined using cross sectional HRSEM and found that layers are formed with sharp interface. The magnetic behaviour of all the films are determined using VSM which shows that saturation magnetization of Ni/Pd/Ni trilayer is greater than that of pure nickel film. Acknowledgements. One of the authors T.A.R acknowledges UGC-UPE-Phase II for its financial assistance in the form of fellowship. References [1] K. Dhanapal, T.A. Revathy, M. Anand Raj, V. Narayanan, A. Stephen, 2014. Magnetic anisotropy studies on pulsed electrodeposited Ni/Ag/Ni trilayer, Applied Surface Science, DOI: 10.1016/j.apsusc.2014.06.058 Novel magnetic materials prepared by electrodeposition techniques: arrays of nanowires and multi-layered microwires, Journal of Alloys and Compounds, 2004, 18-26 DOI: 10.1016/j.jallcom.2003.09.040 [3] Electronic and magnetic properties of Pd-Ni multilayers: Study using density functional theory, Journal of Magnetism and Magnetic Materials, 3478-3482, DOI: 10.1016/j.jmmm.2009.06.059 [4] J.W. Feng, Magnetic anisotropy of sputtered Ni/Ag multilayers, Journal of Magnetism and Magnetic Materials, 1996, 27-32 DOI: 10.1016/0304-8853(95)00445-9
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