Electroplated Fe-Pt thick films prepared in plating baths with various pH values

Abstract

Fe-Pt thick-films were electroplated on a Ta substrate using a direct current, and the effect of the pH value of the plating bath on the magnetic properties of the films was evaluated. For the films prepared from the baths with the same bath composition, the Fe composition and the thickness increased with increasing the pH value. In order to remove the effect of the change in the film composition on the magnetic properties, we controlled the film composition at approximately Fe50Pt50 or Fe60Pt40 by the change in the amount of the iron sulfate. The remanence of the annealed Fe60Pt40 films did not depend on the pH value clearly, and showed almost constant value of 0.75 T. We obtained the large coercivity of approximately 460 kA/m in the pH value from 4 to 7. Since the Fe52Pt48 film prepared at pH ≈ 4 shows much higher (BH)max value of 70 kJ/m3 than that of 57 kJ/m3 for our previously-reported Fe50Pt50 film (pH ≈ 2), we concluded that slight higher pH value than not-adjusted one (pH ≈ 2) is effective to increase the coercivity.

Effect of Na ions in plating baths on coercivity of electroplated Fe-Pt film-magnets

“…As shown in Fig.4 (a), the coercivity increases with increasing the NaCl content, and this result implies that NaCl (Na + ions or Clones) affects the coercivity of the annealed films. As mentioned in "INTRODUCTION", we have already confirmed that the addition of NaOH increases the coercivity [4]. From the results for the previous study and Fig.4 (a), we considered that the Na ion concentration is an important factor to obtain high coercivity for the electroplated Fe-Pt film-magnets because the Clions in the plating bath don't increase by the addition of NaOH.…”

“…We recently reported Fe-Pt thick film-magnets (1-20 μm in thick) prepared in citric-acid-based plating baths, and confirmed that the coercivity of the Fe60Pt40 film-magnet increases from 180 to 460 kA/m when the pH value increases from 2 to 4 [4]. It is wellknown for typical electroplated films that pH values are one of important plating parameters to determine structural and magnetic properties, and some researchers have reported the pH-adjusted plating baths for electroplated Fe-Pt films [5][6][7].…”

Electroplated FePt Films for Micromechanical Magnetic Sensors

“…Electroplating is an efficient technique to produce thick functional materials [ 9 ] such as ferromagnetic films. [ 16 ] CoNiMnP [ 17 ] and FePt [ 18 ] are ferromagnetic materials that possess excellent intrinsic corrosion and magnetic properties and can be electrically deposited. In case of FePt alloys, the atomic ratio of Fe to Pt is an important parameter.…”

Improvement in surface conditions of electroplated Fe-Pt thick-film magnets

“…Some researchers have reported Co-Pt thick-film magnets (2 -25 µm) using electroplating methods, 3,4 and we have also reported some Fe-Pt thick-film magnets (>10 µm) on a Ta substrate with high coercivity (>700 kA/m). 5,6 Although the Fe-Pt thick films in our previous studies showed high coercivity, many cracks were observed on the surface of the annealed films. As electroplated Co-Pt thick films reported by Oniku et al 7 also have many cracks, a reduction in the cracks is an important study for (Fe, Co)-Pt thick-film magnets.…”