Tuning the magnetic properties of multisegmented Ni/Cu electrodeposited nanowires with controllable Ni lengths

Abstract

The fabrication of segmented Ni/Cu nanowires (NWs), with tunable structural and magnetic properties, is reported. A potentiostatic electrodeposition method with a single electrolytic bath has been used to fabricate multisegmented Ni/Cu NWs inside a highly hexagonally ordered anodic nanoporous alumina membrane, with diameters of 50 nm and Ni segment lengths (L Ni) tuned from 10 nm up to 140 nm. The x-ray diffraction results evidenced a strong dependence of the Ni NWs crystallographic face-centered-cubic (fcc) texture along the [220] direction on the aspect ratio of the NWs. The magnetic behavior of the multisegmented Ni/Cu NW arrays, as a function of the magnetic field and temperature, is also studied and correlated with their structural and morphological properties. Micromagnetic simulations, together with the experimental results, showed a dominant antiferromagnetic coupling between Ni segments along the wire length for small low aspect-ratio magnetic segments. When increasing the Ni segments' length, the magnetic interactions between these along the wire became stronger, favouring a ferromagnetic coupling. The Curie temperature of the NWs was also found to strongly depend on the Ni magnetic segment length. Particularly the Curie temperature was found to be reduced 75 K for the 20 nm Ni segments, following the finite-size scaling relation with ξ 0 = 8.1 Å and γ = 0.48. These results emphasize the advantages of using a template assisted method to electrodeposit multilayer NWs, as it allows an easy tailor of the respective morphological, chemical, structural and magnetic properties.

Magnetic behaviour of multisegmented FeCoCu/Cu electrodeposited nanowires

“…In addition, the concentration of Cu in the ferromagnetic alloy is very low. This agrees with previous assumptions that, when using low concentrations of Cu in the electrodeposicion solution, the amount of Cu that incorporate to the layers when applying the FeCo activation voltage is very small and do not significantly change the magnetic properties of FeCo alloys [21,23].…”

“…Therefore, using a template process in the electrochemical deposition is an excellent method to grow NWs and enables the tuning of the composition and the morphology of multisegmented structures [14] [15,16,17]. Segmented NWs with a magnetic/nonmagnetic mutilayered structure grown by pulsed electrodeposition have been highly investigated in the last years: Co/Cu [18,19,20], Ni/Cu [21,22,23] [24], Fe/Cu [25,26], CoFeB/Cu [27], CoFe/Cu [28,29,30], CoNi/Cu [31,14], CoPt/Pt [32], CoFe/Au [33], Ni/Au [34,35], etc.. Most of these works aim the application of spin valves and the exploration of the giant magnetoresistance effect [36] [37,38].…”

The Role of Cu Length on the Magnetic Behaviour of Fe/Cu Multi-Segmented Nanowires

“…An important class of NWs for applications in magnetic devices is the multi-segmented [ 13 , 14 ] one. The combination of multilayers of different materials, both magnetic and non-magnetic, has been spreading much interest due to the magnetic capability to control the interactions and the effect of magnetic anisotropy obtained by only varying the metal type and segment lengths [ 15 , 16 , 17 ].…”

“…The combination of multilayers of different materials, both magnetic and non-magnetic, has been spreading much interest due to the magnetic capability to control the interactions and the effect of magnetic anisotropy obtained by only varying the metal type and segment lengths [ 15 , 16 , 17 ]. In this sense, we can highlight some studies on multi-segmented NWs that employed Ni/Au [ 18 , 19 ], Ni/Cu [ 13 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ], CoNi/Cu [ 27 ], NiFe/Cu [ 28 ], FeGa/Cu [ 16 , 17 ], Co/Cu [ 29 , 30 , 31 , 32 ], and Co/Au [ 33 ]. Because of particular advantages, such as their high saturation magnetization [ 34 ] and the large possibility of modulation of their magnetic properties [ 35 ], systems with FeCo alloys (i.e., CoFeB/Cu [ 36 ], CoFe/Au [ 35 ], CoFe/Cu [ 37 , 38 , 39 , 40 , 41 ]) have been well studied.…”

Arrays of Ni/Co Nanoparticles within a Nanostructured Silicon Host

“…It is generally fabricated by etching (plus selected deposition steps) and thus involves relatively straightforward and low‐cost processes. Template materials, such as porous alumina or porous silicon (PSi) which offers a 3D porous structure, are often used for electrodeposition of magnetic metals within the pores. The deposited nanostructures (particles, wires) have been investigated with respect to their magnetization reversal processes with the concomitant domain wall motion and the interactions among them .…”