Influence Of Electrodeposition Condition On Magnetic Properties Of FeCo-based Soft Magnetic Film

Recently, soft magnetic materials thin films have been increasingly applied in industry accompanying the rapid development of communication technology and electronics industry. The basic demands for soft magnetic thin films operated in the GHz frequency range include high permeability, high saturation magnetization and high cut-off frequency. FeCo-based alloy has been studied systematically because of their highest saturation magnetization. The FeCo-based alloy thin films also have potential applications in high frequency electromagnetic devices such as magnetic sensors, integrated inductor and magnetic reading.Although soft magnetic thin films with excellent high frequency magnetic properties have been prepared in laboratory by sputtering, molecular beam epitaxy (MBE) and so on, these methods are too expensive to be used in industry because they require high vacuum. Comparatively, electrodeposition has been widely used in industry because of its low capital cost, high deposition rate and easy operation while its process is in solution. However, in order to be used in industry, the electrodeposition parameters which would to be prepared soft magnetic films still need to be studied. In this work, the composition, structure and magnetic properties of Fe-based thin films were investigated as a function of electrodeposition parameter such as potential, current density, temperature, additives and stirring process.1) The electrodepotion parameter, such as potential, temperature, sodium citrate and thiourea concentration were systematically studied during the FeCoZr films prepared process. Strong in-plane uniaxial magnetic anisotropy (IPUMA) could be induced in thick films. The resonance frequency fr of FeCoZr films is also adjust range1.3to3.2GHz by changing electrodeposition temperature. By increasing sodium citrate concentration, the easy axis coercivity of FeCoZr films decrease from55to29Oe. Despite the FeCoZrS films lose IPUMA when thiourea add in solution, with the thiourea concentration increasing the resonance frequency of FeCoZrS films also increase from0.4to2GHz.2) Ultrasound was used in the process of electrodepositing FeCoZrS and FeCo. Ultrasound could control the adsorption and decomposition of thiourea molecular, and improve the evolution and adsorption of hydrogen. With the ultrasound power increasing, the Co content of FeCoZrS films increases. The crystal structure becomes bcc, fcc and hep co-existence, while the coercivity increase from40to68Oe. The ultrasound also smoothes the surface of FeCo films, the easy axis coercivity decrease from44to24Oe. The IPUMA could be induced in FeCo and FeNi films by mechanical stirring. These may be caused by the effect of inclined surface shape and oblique columnar crystals.3) We have successfully prepared FeCoCd films onto ITO conductive glass substrates by electrodeposition. The electrodeposition parameter, such as Cd2+concentration, current density and temperature were systematically studied. The FeCoCd film with excellent magnetic properties is obtained under the condition:the Cd2+concentration is0.003M/L, the current density is12.7mA/cm2, the deposition temperature is50℃. The easy and hard axis coercivity of typical FeCoCd film are5and4Oe, respectively. The saturation magnetization is13.85kGs. The IPUMA field is56Oe while the resonance frequency is3.0GHz, implying that the film is promising for high-frequency applications.