Production of CoNiFe thin film alloys by electrodeposition technique and their properties

AbstractMS.c. ThesisPRODUCTION of CoNiFe THIN FILM ALLOYS BY ELECTRODEPOSITIONTECHNIQUE and THEIR PROPERTIESHarun KAYAInonu UniversityGraduate School of Natural and Applied SciencesDepartment of Physics74 + xiii pages2005Supervisor: Yrd. Doç. Dr. Funda Ersoy ATALAYIn this thesis, NiFe and CoNiFe magnetic alloys were prepared by electrodepositiontechnique on thin Cu wires under different electrochemical bath conditions. Firstly,magnetoimpedance effect, MI, in NiFe/Cu wire with various plated NiFe thicknesses wasinvestigated. MI results show that the frequency where the maximum MI occurs, decreaseswith increasing plating thickness. The magnitude of the MI ratio under H= 7400 A/m wasobtained % 750 for 180 minutes plated wire at 55 kHz driving current frequency. From theEDX microanalysis, the film composition was evaluated to be 78.021 % Ni, 19.329 % Fe andalso 1.4% S and Cl. The coercivity of this film was ~94 A/m.Secondly, Co substitution to NiFe films was investigated. In order to obtain the bestmagnetic properties and surface appearances the CoNiFe films were produced at variouselectrolysis bath pH, while the other electrolysis bath conditions, such as; metal saltsconcentration, plating voltage, plating time, plating temperature were kept constant. Thehighest MI ratio, 161.609 % at 145 kHz driving current frequency and 51.589 A/m coercivitywas obtained for the pH 2.4 solution in CoNiFe/Cu wire. It was also evaluated from EDXspectrum, this film has 22.14 %Co, 59.94 % Ni, 17.92 % Fe composition with no impurities.Coercivity increases with increasing electrolysis bath pH.In order to study the effect of the compositions on the magnetic properties of CoNiFefilms, various concentration of Co+2 and Fe+2 sulfate salts were added into the electrolysisbath. CoNiFe/Cu films with 32 different compositions were produced. When the percentageof Co was increased, the coercivity of the films was increased. It was also observed that themagnitude of MI ratio under the H=7400 A/m can reach 299.519 % at 40 kHz driving currentfrequency for 180 minutes plated wire at pH 2.6. This sample has a composition of 18.97 %Co, 49.60 % Ni, 31.43 % Fe with no impurities.KEYWORDS: NiFe, CoNiFe magnetic films, electrodeposition, magnetoimpedance effect