Magnetization reversal properties and magnetostatic interactions of disk to rod-shaped FeNi layers separated by ultra-thin Cu layers

Abstract

From fast magnetic memories with low-power consumption to recording media with high
densities, realizing the magnetization reversal and interaction of magnetic layers would allow for
manipulating the ultimate properties. Here, we use a pulsed electrochemical deposition technique
in porous alumina templates (50 nm in pore diameter) to fabricate arrays of nanowires, consisting
of FeNi layers (26−227 nm in thickness) with disk to rod-shaped morphologies separated by
ultra-thin (3 nm) Cu layers. By acquiring hysteresis curves and first-order reversal curves
(FORCs) of the multilayer nanowire arrays, we comprehensively investigate magnetization
reversal properties and magnetostatic interactions of the layers at different field angles (0° θ
90°). These involve the extraction of several parameters, including hysteresis curve coercivity
(H c
Hyst), FORC coercivity (Hc
FORC), interaction field distribution width (ΔHu), and irreversible
fraction of magnetization (IF m) as a function of θ. We find relatively constant and continuously
decreasing trends of Hc
Hyst when 0° θ 45°, and 45°<θ 90°, respectively. Meanwhile,
angular dependence of H c
FORC and IF m shows continuously increasing and decreasing trends,
irrespective of the FeNi layer morphology. Our FORC results indicate the magnetization reversal
properties of the FeNi/Cu nanowires are accompanied with vortex domain wall and single
vortex modes, especially at high field angles. The rod-shaped layers also induce maximum ΔH u
during the reversal process, owing to enhancements in both magnetizing and demagnetizing-type
magnetostatic interactions.