Structural and Uniaxial Magnetic Anisotropy of Co1-XMgX(X = 0.04–0.12) Nanowires in Alumina Templates

Abstract

The nanoporous anodized aluminum oxide (AAO) templates were synthesized by two-step anodization in a solution of 0.5 M phosphoric acid at 60 V and temperature T ~ 0 °C. The CoMg nanowires were synthesized by template-based AC Electrodeposition technique at different voltages by AC source 13–17 V at room temperature. These CoMg nanowires were investigated via different characterization techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). The SEM result shows that nanowires have average diameter about 150 nm and length about 23 μm. The EDX reveals that nanowires only consisted of Mg and Co atoms, and atomic ratio of Mg/(Co + Mg) showed increasing tendency with deposition voltage which depicts that higher AC electrodeposition voltage is more suitable for Mg-rich deposition. The XRD results show that CoMg nanowires have hexagonal crystal structure with polycrystalline nature. The MH loops confirm that nanowires are soft ferromagnetic with uniaxial magnetic anisotropy. It is observed from angular dependence of coercivity that magnetization reversal mechanism occurs by a combination of curling and nucleation mode. The squareness (Mr/Ms) is found to be 0.24 along nanowires and 0.16 perpendicular to nanowire axis suggesting that easy magnetization direction lies along the nanowires. The effective anisotropy is observed along the nanowire axis due to dominance of shape anisotropy and suppression of dipole-dipole interactions among nanowires.