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 (Hc Hyst), FORC coercivity (Hc FORC), interaction field distribution width (ΔHu), and irreversible fraction of magnetization (IFm) 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 Hc FORC and IFm 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 ΔHu during the reversal process, owing to enhancements in both magnetizing and demagnetizing-type magnetostatic interactions.