Effect of Nonuniform Morphology and Crystalline Structure on the Effective Magnetic Anisotropy in Fe, Co, and Ni Nanowire Arrays

Abstract

The phenomenon of shape anisotropy predominantly constitutes the principal factor influencing effective anisotropy, serving as a significant determinant of the magnetic characteristics of one-dimensional ferromagnetic nanostructures, materials that hold substantial promise for a diverse array of applications in the domains of electronics and biomedicine. However, it is noteworthy that effective anisotropy may be modulated through the manipulation of various other forms of anisotropy, thereby facilitating the tuning of the magnetic properties of nanowire arrays without necessitating alterations to their spatial curvature. In this study, we elucidate the characteristics of nanowire arrays with varying lengths and compositions, which have been electrochemically synthesized utilizing identical porous templates. Through a range of experimental methodologies, we establish a correlation between atypical magnetic behavior and the underlying morphology and crystalline structure of the nanowires. We attribute the pronounced magnetostatic interactions observed within cobalt (Co) nanowires to the presence of significant local uniaxial magnetocrystalline anisotropy, along with a nanostructure oriented perpendicular to the longitudinal axis of the nanowire. Furthermore, we examine the repercussions of substantial discrepancies in the lengths of iron (Fe) nanowires on the magnetostatic field distribution. Our analysis employs mean field theory, incorporating the contributions of various anisotropies present within the system, as well as the non-uniform lengths of the nanowires. Ultimately, through micromagnetic simulations, we investigated the stray fields present within the nanowire array and delineated how strong magnetocrystalline anisotropy and the variability in length affect their spatial distribution.