Fixed vortex domain wall propagation in FeNi/Cu multilayered nanowire arrays driven by reversible magnetization evolution

Abstract

While studying domain wall (DW) propagation in magnetic nanowires (NWs) may pave the way for future research and technological
applications in recording heads and novel sensors, no attention has been paid to the investigation of magnetic reversal modes in multilayered
NWs using angular first-order reversal curve (AFORC) analysis. Here, the magnetization reversal process of uniform FeNi/Cu NW
arrays with a diameter of 45 nm electrodeposited in the anodic aluminum oxide template is systematically studied by AFORC analysis for
the field angle θ (0° ≤ θ ≤ 90°) and compared with the average magnetic behavior of reversal modes based on conventional hysteresis loop
measurements. The FeNi segment aspect ratio is kept constant at about 5, whereas the Cu segment length (LCu) increases from 2.5 to
25 nm. AFORC coercivity increases continuously with increasing θ, indicating that the NWs reverse their magnetization by nucleation and
propagation of vortex DW (VDW). At θ = 0°, the respective hysteresis loop coercivity and magnetostatic coupling between FeNi segments
along the NW length are reduced by increasing LCu from 2.5 to 25 nm, resulting in an enhancement in the reversible fraction of NWs
from 10% to 48%. However, the VDW reversal mode is not influenced by the increase in NW reversibility as a function of θ for the
different LCu, which arises from constant properties of the FeNi segments. The AFORC analysis of the reversal mechanism is also found to
be in agreement with recent angle-dependent anisotropic magnetoresistance measurements in single multilayered NWs.