Effect of additional element (Fe, Zr, Ta) for Co-Cr films deposited by targets facing type of sputtering

Abstract

In order to improve both magnetic properties and wear resistance of Co‐Cr films for perpendicular magnetic recording media, the effect of the addition of a small amount of Fe, Zr, and Ta to the Co‐Cr binary alloy films has been investigated. They were deposited with a targets facing type sputtering (TFTS) apparatus. (i) The addition of a small amount of Fe (K_⊥ (K_⊥=K_u−2πM²_s). The K_⊥ has a negative value at Fe content above 1 at. %. Consequently, the recording characteristics become worse as Fe content increases. (ii) The addition of Zr leads to a remarkable decrease of grain size and improvement of surface smoothness along with an increase of wear resistance. It also causes evident decrease in K_u and saturation magnetization M_s. However, both K_⊥ and remanence ratio M_r⊥/M_r∥ are increased by the addition of a small amount of Zr up to 0.5 at. %, though they decrease steeply with further increase of Zr content above 1 at. %. (iii) The addition of Ta shows almost the same tendency as Zr for the film structure and wear resistance. It also causes the decrease of K_u. But the K_⊥ increases with an increase of Ta content up to 0.5 at. % and takes nearly constant value at Ta content above 0.5 at. %, since the M_s of the film decreases remarkably as Ta content increases. M_r⊥/M_r∥ increases gradually from 2.5 to 3.6 as Ta content increases. Consequently, the addition of a small amount of Ta is effective for improving both recording characteristics and wear resistance.