Linear diameter dependence magnetization of Fe-CoNi core–shell nanostructures

•Synthesis of Fe-CoNi core-shell nanostructures in the nanopores of AAO templates by using two step-step electrodeposition route.•XRD analysis of CoNi NTs and Fe-CoNi core-shell nanogeometry were confirmed to be in fcc phase and bcc-phase.•The average thickness of Fe is found to be 14.377 nm.•Magnetization reversal was determined by coherent mode for smaller diameters (50 nm and 100 nm of AAO tem-plates) whereas curling mode was dominant for larger diameters (200 nm and 250 nm of AAO templates) and combination of coherent and curling magnetization reversal for 150 nm diameter.•Linearly fitted MS/A as the diameter of AAO nanotemplates increased which were earlier reported in the 2-D nanogeometries. Core–shell nanoarchitectures are novel classes of nonstructural materials for their capacious applications. Iron (Fe) electrodeposited inside Cobalt-Nickle (CoNi) alloy nanotubes (NTs) were synthesized using two-step DC electrodeposition method within the nanopores of anodized aluminum oxide (AAO) template. The X-ray diffraction and electron microscopy confirm the presence of body-centred cubic (bcc) phase structure for Fe and face-centered cubic (fcc) for CoNi at core and shell region respectively. A comparative study of magnetization reversal mechanism has been done by verifying the angular dependence of coercivity which further in terms of thermal activation over an energy barrier with a 3/2 power dependence on the field. Furthermore, the parallel magnetization per unit area (MS/A) is found to be strongly dependent on the diameter of AAO templates, which shows a linear response as the diameter increases.