Features of Electrochemical Synthesis, Structure, and Magnetometry of Iron, Cobalt, and Nickel Nanowires in a Porous Anodic Aluminum Oxide Matrix

Porous anodic aluminum oxides were formed by electrochemical methods. Nanowires with a diameter of 85 nm and a length of 40–50 μm with an aspect ratio of 500–625 made of nickel, cobalt, and iron were electrochemically formed from aqueous solutions of electrolytes. The obtained nanowire samples were studied using SEM and magnetometry of a vibrating sample. The result of the dipole–dipole interaction in an ensemble of densely arranged nanowires is an increase in the barrier for coordinated remagnetization of the entire array. The process of remagnetization occurs through the incoherent movement of the domain walls, which leads to a change in the mechanism of remagnetization, which is reflected in the characteristics of the gentle hysteresis loops and, consequently, a decrease in the quadraticity of the loop. Such nanowires have a number of unique properties, finding applications from nanospintronics, sensors, nonlinear optics metamaterials, chemical reaction catalysts, to cancer thermotherapy. By changing the composition and geometry, it is possible to purposefully shape the magnetic properties of nanowires, such as saturation magnetization, coercive force, and control the spin structure, forming new classes of nanostructures. The technology of creating one-dimensional (1D) nanoobjects using porous anodic aluminum oxide templates involves electrochemical crystallization within the pores of metal elements, particularly ferromagnets such as iron, nickel, cobalt, and their alloys. These 1D objects possess unique properties, finding applications in nanospintronics, sensors, nonlinear optics, metamaterials, chemical reaction catalysts, and cancer thermotherapy. By altering the composition and geometry, one can purposefully manipulate the magnetic properties of these materials, such as saturation magnetization and coercive force, and control spin structure, leading to the development of new classes of 1D structures, including segmented nanowires. This research focuses on these aspects of electrochemical crystallization for ferromagnets. Aluminum templates with an average pore size of 80 nm are created through electrochemical anodizing. Nanowires of iron, nickel, and cobalt are then grown within these pores using electrochemical deposition. The structure of the ferromagnets is analyzed using scanning electron microscopy and X-ray diffraction. The magnetic properties of the resulting nanowires are examined through vibrating sample magnetometry.