Chemically Deposited Cobalt-Phosphorus Films for Magnetic Recording

Thin magnetic films of cobalt‐phosphorus chemically deposited from a modified Brenner bath are reported in this paper. Detailed data are presented to demonstrate the role of deposition conditions on thickness, phosphorus content, and magnetic properties of the films. The films are much thinner than have been reported previously and exhibit a coercivity range of approximately 80 to 900 oe with a coercivity‐thickness relation . This is similar to that reported by Fisher and Chilton for much thicker films. Some of the variables which control the magnetic properties of the deposited film are shown to be: film thickness, bath p H, hypophosphite concentration, and bath temperature; the first two are the dominant factors and overshadow any influence that the codeposited phosphorus may have. An account of the apparatus used for precise and automatic control of the bath p H is given. Well‐adherent mirror‐like films which are suited for conventional high‐density magnetic recording, as well as Kerr magneto optical readouts, are obtained