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.