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

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), FORC coercivity (H), interaction field distribution width (ΔH), and irreversible fraction of magnetization (IF) as a function ofθ. We find relatively constant and continuously decreasing trends ofHwhen 0° ≤θ≤ 45°, and 45° < θ≤ 90°, respectively. Meanwhile, angular dependence ofHandIFshows 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 ΔHduring the reversal process, owing to enhancements in both magnetizing and demagnetizing-type magnetostatic interactions.