Electroless CoNiFeB soft magnetic thin films with high corrosion resistance

A new soft magnetic CoNiFeB thin film with high saturation magnetic flux de nsity, B-S and good corrosion resistance has been prepared by using an elec troless deposition method. The electroless CoFeB thin film has high B-S but a poor corrosion resistance compared with the electrodeposited NiFe (80-pe rmalloy) film. The addition of Ni to the CoFeB film improves corrosion resi stance without affecting its soft magnetic properties. One of the best CoNi FeB films prepared had a composition of Co77Ni13Fe9B1 with excellent magnet ic and electrical properties (high B-S = 1.5-1.7 T, low coercivity, H-C = 1 .2 Oe, low magnetostriction, lambda (S) = 2.0 x 10(-6), and moderate resist ivity, rho = 40 mu Ohm cm). The new CoNiFeB thin film is suitable for use a s a core material for the next generation of merged MR-heads. (C) 2000 Else vier Science B.V. All rights reserved.