Electrodeposited hard-magnetic Fe 50 Pd 50 nanowires from an ammonium-citrate-based bath Darja Pec ˇko a,⇑ , Kristina Z ˇ uz ˇek Roz ˇman a , Nina Kostevšek a , M. Shahid Arshad a , Boštjan Markoli b , Zoran Samardz ˇija a , Spomenka Kobe a a Department for Nanostructured Materials, Joz ˇef Stefan Institute, Ljubljana, Slovenia b Department for Materials and Metallurgy, Faculty of Natural Science and Engineering, University of Ljubljana, Slovenia article info Article history: Received 20 August 2013 Received in revised form 24 February 2014 Accepted 26 March 2014 Available online 3 April 2014 Keywords: Electrodeposition Fe–Pd nanowires L1 0 phase Magnetic properties abstract Fe–Pd nanowires were synthesised in anodic alumina templates by applying both potentiostatic and pulsed electrodeposition regimes. When using potentiostatic deposition, only fragmented nanowires were obtained; however, the use of pulse deposition was shown to be effective for producing solid nano- wires. In order to achieve this, different on-times for the deposition and off-times between the pulses in an electrolyte with a constant concentration of Fe(III) and Pd(II) ions at pH 9 were employed. Homoge- neous nanowires with the composition Fe 55±5 Pd 45±5 , lengths of 2.5 lm and diameters of 200 nm were synthesised under the following pulsed conditions E on = 1.4 V, t on = 2 s and E off = 0.1 V, t off = 10 s for 5000 cycles. The as-deposited nanowires had a fcc crystal structure and were magnetically soft (H C  5 kA/m) with the easy axis of magnetization perpendicular to the long axes of the nanowires, mainly due to the dipolar coupling within the template. In order to promote the ordering into the L1 0 phase, annealing in the temperature range 400–700 °C for 1–9 h in Ar + 7% H 2 was performed. The highest coercivity of 122 kA/m was achieved by annealing at 600 °C for 5 h. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction One-dimensional nanostructures, such as nanowires, nanorods and nanotubes, have been the topic of many investigations due to their small size and unique and tuneable properties, all of which make them appropriate for a very broad range of applications, such as electronic (in nano/micro-electro-mechanical systems), thermo- electric devices and for sensing in biology and chemistry [1–3]. There have been many methods used for the synthesis of one- dimensional nanostructures, such as: chemical vapour deposition [4,5], vapour–liquid–solid (VLS) growth [6], lithographically pat- terned nanowire electrodeposition [7], reductive sulphidization [8], hydrothermal reduction [9], sol–gel [10] and template-assisted electrodeposition. Template-assisted electrodeposition is, in com- parison to the other methods, highly selective, since it relies on electron transfer, which is the fastest along the highest conductiv- ity path. Therefore, it offers the possibility to deposit different nanostructures with a high technological potential. When using nanoporous membranes it is possible to deposit and tailor the nanostructure’s properties with high aspect ratios that are densely and continuously packed and possess a high crystallinity [11]. The most commonly used membranes are polycarbonate (PC) and anodized alumina oxides (AAO). The AAO-based template has been considered as an ideal template as it possesses many desirable characteristics, including tuneable pore dimensions, good mechan- ical strength, thermal stability and ordered nanopores with a high density (10 9 –10 11 cm 2 ) [11,12]. Successful depositions of metal nanowires, such as Ni, Pd, Cu, [2,13–15] and different alloys, Co–Zn, Co–Cu, Cd–Se, Co–Pt, Fe–Pt [16–19] and Fe–Pd [3,20–23], have been performed in AAO templates. Nanostructures with an ordered L1 0 phase have attracted a lot of attention in the past few years due to their large magnetocrystalline anisotropy along the c-axis of their tetragonal crystal structure, which makes them appropriate for high-density magnetic recording media [24–26]. So far, many studies and investigations have been made on the Co–Pt and Fe–Pt systems because they have higher magnetocrys- talline anisotropies (6.6 and 4.9 MJ/m 3 ) [25]. In comparison to Co–Pt and Fe–Pt, Fe–Pd (1.8 MJ/m 3 ) [23] possesses a lower a mag- netocrystalline anisotropy; however, the Fe–Pd alloy exhibits a lower disorder–order transition temperature, and the low cost of Pd in comparison with Pt makes this material interesting for http://dx.doi.org/10.1016/j.jallcom.2014.03.156 0925-8388/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Address: Department for Nanostructured Materials, Joz ˇef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia. Tel.: +386 1 4773 945; fax: +386 1 4773 221. E-mail address: darja.pecko@ijs.si (D. Pec ˇko). Journal of Alloys and Compounds 605 (2014) 71–79 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jalcom