Torque magnetometry analysis of magnetic anisotropy distribution in Ni nanowire arrays

Abstract

Highly ordered arrays of Ni nanowires have been prepared by pulsed electrochemical deposition into nanopores of anodic alumina membranes (NAAMs) used as templates. They have been experimentally characterized by magnetic torque measurements and vibrating sample magnetometer (VSM) techniques in order to determine the magnetic anisotropy of the hexagonal array of nanowires. A detailed analysis of the experimental data has been performed based on a phenomenological model taking into account the influence of the nanowire shape anisotropy added to the dipolar magnetostatic interactions among them. An overall agreement is obtained between the simulations derived from the model and the experimental magnetic torque anisotropy curves.

Electroplating and magnetostructural characterization of multisegmented Co54Ni46/Co85Ni15 nanowires from single electrochemical bath in anodic alumina templates

“…The combination of low magnetocrystalline anisotropy of face-centered cubic (fcc) Ni and high magnetocrystalline anisotropy of hexagonal close-packed (hcp) Co, together with the high solubility of Co atoms in the crystalline lattice of Ni and vice versa for a wide range of relative concentrations [18], allows for the design of a material composition with tunable magnetic properties. The effective magnetic anisotropy energy is determined by the competition between the shape and magnetocrystalline anisotropies, together with the magnetostatic dipolar interactions among nanowires, being possible to tune the easy magnetization direction of the system between the longitudinal and perpendicular directions with respect to the nanowire axis [19,20]. Additionally, the study on multisegmented magnetic nanowires, comprising alternate single segments of soft and hard magnetic materials with well-controlled thicknesses and separated by non-magnetic interspacers, has recently drawn the interest of the scientific community due to the interesting magnetization reversal processes that take place in these nanostructured materials that may allow for the design of multistable magnetic systems that are capable of storing several bits of information in a single nanowire [21].…”

Functional Fe–Pd nanomaterials synthesized by template-assisted methods

“…The values of some characteristic magnetic parameters as coercivity (H C ), reduced remanence (m r ¼M r /M s ) and anisotropy field (H K ), of the produced samples, are collected in Table 1. As it can be compared, the Fe 80 Pd 20 thin film has the highest anisotropy field, as obtained by numerical derivation of the descent from saturation to the remanent state of the OOP hysteresis loop branch (hard axis), as reported in [14], giving a rough estimation of around 13 kOe, due to the dominant role played by the shape anisotropy.…”

Electrochemical synthesis of magnetic nanowires with controlled geometry and magnetic anisotropy

“…The magnetic behavior of single-element magnetic nanowire arrays is determined by the intrinsic magnetic character of the individual nanowires together with the magnetostatic interactions among them, which are related to the diameter and length of the nanowires and to the porosity of the templates where they are arranged, in addition to the saturation magnetization value of each nanowire's composition (Prida et al, 2007;Vega et al, 2011). While the strong shape anisotropy of the nanowires favors an effective magnetic anisotropy with easy axis parallel to the nanowires, interwire magnetostatic interactions result in a reduction of the effective longitudinal anisotropy (Escrig et al, 2007).…”