Structural and magnetic properties of Fe3Ga alloy nanowires: Effect of post annealing treatment

Abstract

We report on the influence of the annealing temperature on the crystal structure phase change, effective anisotropy energy and magnetization reversal of electrodeposited Fe3Ga nanowires (NWs) with diameter of 80 nm. Scanning transmission electron microscopy (STEM) energy-dispersive X-ray (EDX) spectroscopy technique for the elemental mapping of Fe3Ga NWs showed clearly the homogeneous distribution of Fe and Ga. These NWs are highly aligned to each other and exhibits high geometrical aspect ratio. The crystal structure of these nanowires shows strong dependence on the sintering temperature. X-ray diffraction reflects the highly textured A2-disorderd phase with precipitates of DO3 and L12 phase for assynthesized Fe3Ga NWs. As the annealing temperature increases, the intensity of strong disordered phase A2 or short range order phase DO3 suddenly decreases and grains are textured along the stable L12 phase with small precipitates of DO3 phase. As a result of these structural changes, magnetization reversal mode switches from transverse to a combination of transverse and vortex modes. Angular magnetic response at room temperature is employed to identify the magnetization reversal modes for Fe3Ga NWs. Temperature dependent coercivity response can be understood in terms of thermal activation over an energy barrier with a 32 e power dependence on the field.