Studies on coercivity in Co-Cr thin films by means of a multilayer technique

Abstract

It is known that there is a significant dependence of perpendicular coercivity Hc⊥ of Co-Cr sputtered thin films on thickness δ even if substrate temperature Tsub is constant during film deposition. Such a δ dependence of Hc⊥ suggests the nonuniformity of magnetic properties normal to the film plane. In order to prepare Co-Cr thin films with satisfactory magnetic homogeneity, multilayered films composed of many Co-Cr thin layers were fabricated by the facing targets sputtering (FTS) system. The experimental results indicated that these multilayered films may be magnetically and crystallographically homogeneous. For example, films deposited at Tsub of 150 °C with thicknesses above 1000 Å have Hc⊥ about 1.5 kOe, however, Hc⊥ of the multilayered films piled up with 300-Å-thick Co-Cr layers which are deposited even at Tsub of 150 °C indicate almost the same value as that of the 300-Å-thick unit layer. Those are about 500 Oe regardless of the total thickness of multilayers. Hc⊥ of the multilayered film depends not only on Tsub but also the thickness of the unit layer.