Increase of coercivity and squareness ratio of by ferrite thin films by adding SiO/sub 2/ and substituting Al for Fe

Abstract

Simple Ba ferrite (BaM) and SiO/sub 2/-added BaM (BaM:SiO/sub 2/) and Al substituted BaM (Al-BaM) films were deposited using the facing targets sputtering apparatus on SiO/sub x//Si wafers with Pt seed layers to enhance the c-axis orientation perpendicular to the film plane. Magnetic characteristics of the three kinds of BaM films were investigated and compared. Perpendicular coercivity H/sub c/spl perp// and squareness ratio S/sub /spl perp// of BaM:SiO/sub 2/ films increased to 4.2 kOe and 0.83, respectively, H/sub c/spl perp// and S/sub /spl perp// of Al-BaM films increased to 3.2 kOe and 0.89, but saturation magnetization M/sub s/ decreased to 2.9 kc. The magnetization reversal mechanism of BaM:SiO/sub 2/ and BaM films is not in coherent rotation mode but seems to be in the curling mode. The reason for high H/sub c/spl perp// of BaM:SiO/sub 2/ films is different from that of Al-BaM ones.