Influence of annealing on the structural and magnetic properties of Ni nanowires

The effect of annealing temperature on the structural, morphological and magnetic properties of one-dimensional Ni nanowires has been investigated in this work. Ni nanowires of diameter around 200 nm were fabricated by electrodeposition technique in porous anodic alumina templates of thickness 60 mu m. The room temperature electrodeposited nanowires were annealed at different annealing temperatures viz. 250 degrees C, 350 degrees C and 450 degrees C respectively. It was observed that the crystallinity of the nanowires deteriorates with the increase of annealing temperature. The X-ray diffraction pattern confirmed the face-centred cubic texture of nanowires and scanning electron microscopy revealed that the templates were uniformly filled with Ni. The dynamic properties of a one-dimensional uniform array of Ni nanowires were studied by ferromagnetic resonance (FMR) technique at various frequencies ranging from 10 to 30 GHz. The resonance field and field linewidth were determined by the Lorentzian fits of FMR spectra. The resonance field increases with the increase in annealing temperature and frequency. We observed that the resonance linewidth decreases with the increase in frequency.