IEEE TRANSACTIONS ON MAGNETICS, VOL. 45, NO. 6, JUNE 2009 2475 Electrodeposited CoNiP Hard Magnetic Nanowires in Polycarbonate Membrane V. Sudha Rani , S. AnandaKumar , K. W. Kim , Seok Soo Yoon , J.-R. Jeong ,and CheolGi Kim Department of Materials Science and Engineering, Chungnam National University, Daejeon 305-764, Korea Department of Physics, Andong National University, Andong 760-749, Korea An array of CoNiP magnetic nanowires were grown in polycarbonate membrane using potentiostatic electrodeposition technique under three electrodes configuration. The commercially available track etched polycarbonate membranes of thickness 6 m with pore size of 50 nm diameter were used in these experiments. The electrolyte bath consists of NiCl -6.81 g/l, CoCl -2.76 g/l, NaH PO -2.59 g/l, H BO -2.49 g/l, NaCl-2.20 g/l, Saccharin-0.8 g/l was used for deposition of CoNiP magnetic nanowires. The main aim of this work fo- cuses on growth conditions, structural and magnetic properties of the CoNiP nanowires. In this context first we observed three different growths of nanowire lengths 1.21 m, 4.31 m and 6 m at three different deposition times 30 min, 60 min, and 90 min, respectively. The X-ray diffraction patterns of CoNiP nanowires have shown the intermixture of fcc and hcp phases. The structural properties of the CoNiP nanowires were observed using scanning electron microscope (SEM). The magnetic properties of the CoNiP nanowires were ob- served using vibrating sample magnetometer (VSM), which show hard magnetic properties with no preferential magnetization direction of the nanowires having high coercivity values around 500 Oe. Index Terms—Electrodeposition, magnetic properties, nanoporous templates, nanowires. I. INTRODUCTION H ARD magnetic nanowires have been drawn much attention due to their potential in biosensing applica- tions, nanowire sensors, high density perpendicular magnetic recording media and also their additional capability in MEMS devices[1]–[6]. Especially, CoNiP magnetic nanowires are much interested because of its larger coercivity and higher saturation magnetization [7]. However, there are some reports on Co and Ni based electrodeposited nanowires for numerous applications [8]–[11]. The CoNiP ternary alloy based nanowires are having hard magnetic properties with much higher coer- civity than individual Co and Ni nanowires. The electrodeposition method is mostly used for processing nanostructured materials that require specific physical and chemical properties [12], [13]. It can be considered as an alter- native approach to conventional lithography methods because it is inexpensive, simple and high throughput technique for mass production. Recently, using electrodeposition technique a significant progress has been made in fabricating an array of nanowires by means of nanoporous templates. Among various nanoporous templates, the track etched polycarbonate membranes are suitable candidates for growing any kind of magnetic nanowires, since they are cost effective, and available with different thickness and pore sizes. The properties of nanowire arrays are directly related to the properties of the nanoporous templates such as the relative membrane thickness, pore size and spatial distribution [14]. The nanowires are not applicable directly in devices when they are embedded in the polycarbonate templatesembedded in template cannot be integrated directly into conventional devices [13]. Hence, the templates must be dissolved after electrodeposition. Manuscript received October 17, 2008. Current version published May 20, 2009. Corresponding author: C. Kim (e-mail: cgkim@cnu.ac.kr). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TMAG.2009.2018657 In this study, potentiostatic electrodeposition technique under three electrodes configuration was employed for growing the CoNiP nanowires into polycarbonate membranes. In this com- munication we have reported the structural and magnetic prop- erties of CoNiP hard magnetic nanowires deposited at three dif- ferent deposition times. II. EXPERIMENTAL PROCEDURE In the three electrodes potentiostatic configuration an 8-cm thin platinum sheet and Ag/AgCl were used as counter and reference electrodes, respectively. A metallic Au film of 200 nm was sputtered on one side of a commercially avail- able track etched polycarbonate membranes (thickness 6 m, with pore size of 50 nm diameter) which is serving as a working electrode. The room temperature electrolyte bath consists of NiCl -6.81 g/l, CoCl -2.76 g/l, NaH PO -2.59 g/l, H BO -2.49 g/l, NaCl-2.20 g/l, Sachharin-0.8 g/l is prepared for deposition of the nanowires [15]. The pH value of the elec- trolyte bath was maintained around at 3.2 during the deposition. Prior to the deposition the membrane was placed in the depo- sition cell filled with distilled water for several hours to make the pores hydrophilic. After the wetting process, the distilled water was replaced with the electrolyte bath just before starting the deposition process. The deposition was carried out at a constant potential of V with respect to the Ag/AgCl reference elec- trode for the reduction of the metallic ions from the electrolyte bath. During the deposition process current-time profiles were recorded to understand the growth rate of the nanowires. The consecutive experiments were carried out by increasing the de- position time to estimate the growth rate of the nanowires. Crystallization properties of the CoNiP nanowires were ex- amined by X-ray diffractometer using Cu-K radiation. The structural properties of the deposited CoNiP nanowires were ob- served using scanning electron microscope. The magnetic prop- erties of the nanowires were investigated using Lake-Shore 7400 series vibrating sample magnetometer before removal of the template. After the measurement, the template was dissolved 0018-9464/$25.00 © 2009 IEEE