A systematic study on electrodeposition, microstructure and magnetization mechanism of CoP core-shell nanowires

https://doi.org/10.1016/j.jmrt.2026.02.092

Although magnetic nanowires (NWs) hold promise for high-density storage and spintronics, controlling their microstructure and magnetic anisotropy remains challenging. This study demonstrates how alternating current (AC) electrodeposition enables the synthesis of Cobalt–Phosphorus (CoP) core-shell NWs with tunable magnetic properties through precise control of the AC parameters and the phosphorus content. CoP NWs were synthesized through AC electrodeposition within highly ordered nanoporous anodic aluminum oxide (AAO) templates. This study systematically investigates the influence of the AC frequency, waveform, and phosphorus content in the electrolyte on the microstructure, composition, and magnetic behavior of the NWs. It is demonstrated that the AC parameters and phosphorus concentration critically govern the structural evolution of Co_100-xP_x NWs, inducing a transition from a purely crystalline phase to a complex coaxial core-shell architecture comprising coexisting amorphous and crystalline regions. Magnetization analysis reveals a ferromagnetic core enveloped by dual shells with weak ferromagnetic or non-magnetic characteristics, dependent on the phosphorus content. Furthermore, the interplay between the AAO template porosity and the NWs’ microstructure dictates their magnetic anisotropy. Temperature-dependent magnetization measurements and the derived Bloch constant for Co_93.2P_6.8 NWs provide evidence of a metastable face-centered cubic (fcc) phase within the core-shell structure. Micromagnetic simulations highlight a stark contrast in domain configuration and magnetization reversal mechanisms between CoP NWs with coaxial core-shell architectures and their pure cobalt counterparts, underscoring the role of phosphorus-induced structural heterogeneity in tailoring magnetic properties. These findings establish AC electrodeposition as a versatile route for engineering functionally graded magnetic nanostructures with tunable anisotropy and switching behavior.