Electroplating of Magnetic Ni-Fe Alloy Thin Films and Their Characterization

Abstract

In magnetic data storage devices field soft magnetic thin films as read and write heads of HDD’s have played a vital role in enhancing the data storage density and data transfer rates. Soft magnetic materials primarily include varieties of Ni-Fe alloys. In the present study NiFe (80:20) permalloy thin film was studied because of its comparable good soft magnetic properties. Electroplating of Ni-Fe thin films was done over copper substrates over a range of temperatures and potentials at a fixed bath composition of Nickel and Iron ions in the ratio of 80:20. Various characterizations such as XRD, SEM, EDS, Stylus surface profilometry and MFM of the prepared sample were done. XRD patterns revealed the formation of Ni-Fe alloy. Crystallite size calculations done from XRD patterns shows that crystal size of deposits increases with increase in bath temperature, hence lattice strain decreases. Morphology of thin films was observed by SEM, grains were spherodized in shape and were clustered due to high surface energy associated with decreased size. EDS analysis confirms the composition of thin films, that emanated to be approximately equal to 80:20 (Ni:Fe) as was desired. Surface properties such as thickness, roughness and waviness of thin film were measured by stylus surface profilometer. Thickness of thin films prepared at different bath temperature and deposition parameters conditions came out to be in the range of 2.5 to 3.0µm, and roughness varied from 0.1 to 1.0 µm. MFM analysis was done to study the magnetic behavior of thin films, differentiate between magnetic and nonmagnetic phase and topography of the deposits prepared at various conditions. More magnetic phase was found in the deposit prepared by electrolytic bath at high temperature as compared to that of low temperature.