Study on magnetic properties of NiFe/Cu multisegmented nanowire arrays with different Cu thicknesses via FORC analysis: coercivity, interaction, magnetic reversibility

Abstract

Two sets of the large hexagonally ordered arrays of Ni30Fe70/Cu multisegmented nanowires (NWs) with different non-ferromagnetic (NFM) thicknesses of 4 and 12 nm were grown by ac pulse electrodeposition method into anodic aluminum oxide templates with a pore diameter of 40 nm and 100 nm inter-pore distance. The shape anisotropy of the single domain (SD) FM segments was varied from symmetrical-shaped (aspect ratio ~ 1) to rod-shaped (aspect ratio > 1). X-ray diffraction result showed a change in the crystalline phase from NiFe BCC (110) to Cu FCC (111) with increasing the NFM thickness. First-Order Reversal Curve (FORC) method was used to study magnetizing and demagnetizing interactions among the SD segments of the multisegmented NW arrays. The study mainly has been focused on the clarification of the effect of NFM thickness on magnetostatic interactions in the presence of high reversibility, which was estimated to be more than 50%. Weakening the magnetizing coupling of the FM segments through increasing NFM thickness is recognized by a ridge along the coercivity axis of the FORC diagram. With increasing the NFM thickness, the demagnetizing interactions decrease which can be a direct consequence of decreasing the magnetizing NFM thickness. Increasing the NFM thickness also leads to increasing the magnetic reversibility which is characterized on FORC diagrams by a shift in the FORC distribution to the lower coercivity values.