Probing the interplay between reversibility and magnetostatic interactions within arrays of multisegmented nanowires

Abstract

Ordered arrays of NiFe/Cu multisegmented nanowires (NWs) are fabricated by
ac pulse electrodeposition method into the 25-lm thick anodic aluminum oxide
templates with a pore diameter of about 40–100 nm inter-pore distance. The
behavior of magnetostatic interactions between neighboring NiFe/Cu NWs as
well between magnetic segments of the same wire related to the NW length and
the magnetic segment thickness is presented. The first-order reversal curves
(FORCs) results for two given magnetic shape anisotropies, a nearly diskshaped
and a rod-shaped one, reveal a single domain magnetic state along with
a constant peak value of FORC coercivity distribution (Hc
FORC). However, the
Major Hysteresis Loop coercivity (Hc
MHL) shows a significant reduction with an
increase in length. In addition, the magnetostatic interaction distribution along
the Hu axis of FORC diagrams shows a weakly decreasing behavior, in disagreement
with existing phenomenological model. In order to resolve this
contradiction, the reversible and irreversible components of magnetization were
measured. For arrays of multisegmented NWs, the contribution of the reversible
components of magnetization rises up to about 70% as NW’s length increases
which is in contrast for arrays of uniform NWs where a nearly zero reversibility
is reported