INVESTIGATION INTO PERPENDICULAR ANISOTROPY COBALT-CHROMIUM FILMS WITH APPLICATION TO WINCHESTER COMPUTER DISCS

Abstract

RF-sputtered CoCr films have been characterized for a variety of deposition conditions, and the most effective parameters which bring about perpendicular anisotropy have been evaluated. In particular bias sputtering has been noted for its role in improving the crystallographic orientation and magnetic properties when applied to the substrate at certain values, hence the root mechanism of the observed improvement has been, as far as possible , investigated . These investigations have, in particular, focused on the extent to which impurity gases are likely to effect the magnetic properties of sputtered films, as well as quantifying the gas contents of the films using as yet unexploited (in this area) method of thermal desorption experiments. In a further attempt to quantify tolerable level of impurity species in the sputtering environment , impurity gases of nitrogen, oxygen and hydrogen, which are commonly present even in high vacuum systems, were intentionally introduced in the sputtering chamber and their effects on both magnetic and crystallographic properties of CoCr were noted . To measure the perpendicular and in-plane magnetic properties of CoCr , a combined polar-transverse Kerr magneto- optic system was costructed , through which direct magnetic measurement of CoCr/NiFe becomes feasible . This method was further exploited to compare volume and surface magnetic properties of CoCr , as measured using a V.S.M and this M-O system. Finally , a CoCr/NiFe W1nchester disc was fabricated on which a recording experiment was successfully performed.