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

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 degrees <= theta <= 90 degrees). These involve the extraction of several parameters, including hysteresis curve coercivity (H ( c ) ( Hyst )), FORC coercivity (H ( c ) ( FORC )), interaction field distribution width (Delta H ( u )), and irreversible fraction of magnetization (IF ( m )) as a function of theta. We find relatively constant and continuously decreasing trends of H ( c ) ( Hyst ) when 0 degrees <= theta <= 45 degrees, and 45 degrees theta <= 90 degrees, 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 Delta H ( u ) during the reversal process, owing to enhancements in both magnetizing and demagnetizing-type magnetostatic interactions.