Synthesis and characterisation of Fe–Pt and Co–Fe–Pt nanocrystalline magnetic thin films electrodeposited from tartrate–alkaline electrolyte solution

Abstract

Fe–Pt and Co–Fe–Pt nanocrystalline thin films were electrodeposited on brass substrates from a tartrate–alkaline plating bath. The composition, crystallographic structure, microstructure, surface morphology and magnetic properties of the Fe–Pt and Co–Fe–Pt alloy films were investigated. Ammonium tartrate and ammonia solution were used as complex forming additives to stabilise the Fe2+ and Co2+ ions and to enhance codeposition with platinum complexes. The as synthesised thin films were characterised by energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, atomic force microscopy, magnetic force microscopy and alternating gradient magnetometer. The energy dispersive X-ray spectroscopy results showed that cobalt was preferentially deposited compared to iron during Co–Fe–Pt film electrodeposition. The scanning electron microscopy results showed that the microstructure of the films consisted of spherical granules and clusters. The XRD showed the formation of a disordered face centred cubic Fe–Pt phase, and all the peaks were shifted to slightly higher diffraction angles with increasing cobalt content. The average crystallite size calculated from XRD peak broadening was <10 nm. Atomic force microscopy characterisation showed that the surface roughness increased with increasing Co content in the film. The magnetic force measured by magnetic force microscopy was found to correlate to the topography of the films. The magnetic properties obtained from alternating gradient magnetometer increased with increasing surface roughness, granule size and clusters of the film. The addition of Co was found to enhance the saturation magnetisation and coercivity.