Electrodeposition of low-stress high magnetic moment Fe-rich FeCoNi thin films

Low-stress high magnetic moment Fe-rich FeCoNi thin films were electrodeposited from acidic chloride baths to investigate the effects of the deposition temperature, solution pH and l-ascorbic acid on film morphology, crystal structure, magnetic properties and film stress. As the deposition temperatures were increased from 23 to 70 °C, the film stress in the FeCoNi films decreased from 260 to 28 MPa at pH 1.5 in the absence of l-ascorbic acid. The film stresses further decreased to approximately 0 MPa when solution pH was increased to 2.15. However, the plating baths became unstable at pH higher than 2.15 because of precipitate formation. On increasing the deposition temperature, the deposit Fe content in the FeCoNi thin films decreased from 83 to 72 atomic percent (at.%) and the Co content increased from 17 to 27 at.%. In the case of the deposit Ni content, it slightly increased with increasing deposition temperature. From the XRD analysis, the change of the preferred planes from the bcc (1 1 0) to bcc (2 0 0) with increasing deposition temperatures was observed. It is believed that the changes in the grain size and the incorporation of impurities during electrodeposition influenced the stress of the FeCoNi films. The presence of l-ascorbic acid enhanced the stability of the baths at high pH meanwhile reducing current efficiencies. With increasing deposit Ni content, magnetic saturation (BS) and parallel squareness slightly decreased and increased, respectively.