Soft magnetic properties and microstructure of high moment Fe-N-Al-O films for recording heads

Fe-N-Al-O alloy films were fabricated by rf reactive sputtering in a mixed Ar+N-2 plasma. The Al and O contents in films were varied by the area ratio of Al2O3 chips placed on an Fe target. We examined the effects of additional elements, such as Al and O, on magnetic and electrical properties of the Fe-N-Al-O films, and we investigated the relationship between soft magnetic properties and microstructure. The permeability reaches a maximum of about 1800, when the Al+O content range is 10-16 at%, Fe-N-Al-O films in this range have 4 pi Ms = 19-20 kG and rho = 60-100 mu Omega cm. The real part of permeability (mu') of the 0.7-mum-thick Fe79N5Al6O10 film remains constant up to 300 MHz, The as-deposited Fe-N-Al-O film showing soft magnetic properties has homogeneous microstructure with a grain size of about 5 nm, It seems that the addition of Al and O to Fe-N films is effective in suppressing grain growth, and contributes to the formation of homogeneous film structure.