Magnetic field annealing dependent magnetic properties of Co90Pt10Co90Pt10 nanowire arrays

Co90Pt10Co90Pt10 alloy and elemental Co nanowires (NWs) are fabricated by electrodeposition in the self-assembled anodic alumina templates. The fabricated NWs are subjected to magnetic field (MF) annealing under 1000 Oe applied magnetic field in a direction parallel to the nanowire axis at 265 °C. The corresponding changes in the saturation magnetization, coercivity, remanent squareness, the shape of hysteresis loops and crystal structure of NWs before and after MF annealing have been investigated. The enhanced magnetic anisotropy has been observed in Co90Pt10Co90Pt10 alloy NWs by MF annealing. The elemental Co NWs have not been affected by MF annealing. The stress relief between the domains and diffusional pair ordering of unlike atoms along the direction of external applied field are thought to be the causes of enhanced anisotropy. Re-annealing of the samples in the absence of magnetic field at 600 °C does not completely remove the enhanced anisotropy. The shape of the NWs is concluded to play major role in persistence of enhanced magnetic anisotropy after high temperature reannealing.