Friction and wear properties of Co-Cr media with oxidized surface layer

In order to improve the durability of Co-Cr films for perpendicular magnetic recording media, effects of partial pressure of oxygen (Po2) on the friction and wear properties of Co-Cr films by reactive sputtering in argon / oxygen gas mixture have been investigated. At Po2below about 0.08 mTorr, there is no significant reduction of the coefficient of friction (µk) of Co-Cr films, though Cr in the films is selectively oxidized at the column boundary. Above about 0.08 mTorr, sputtered Co-Cr films consist of the oxides of both Co and Cr, and µkdecreases drastically. In particular, Co-Cr films deposited at Po2from 0.1 to 0.2 mTorr take a considerably low value of µkand have a good wear resistance. Accordingly, about 200 Å thick Co-Cr film by reactive sputtering at Po2of 0.2 mTorr was deposited on the surface of Co-Cr perpendicular magnetic films as a protective layer for Co-Cr flexible disc media. The oxidized surface layer has remarkably improved the wear resistance of Co-Cr media.