Cobalt-based Alloy Magnetic Thin Film Microstructure And Magnetic Properties

Magnetic recording materials have been widely applied in computer and electron devices. With the development of the electron industry, the area of single recorded bit becomes smaller and smaller, and the areal recording density in magnetic recording is required to become higher and higher. Therefore, it becomes increasingly important to further improve the properties of magnetic recording media.In this thesis, C/CoCrTa/X (X=Cr, Ti) and Cr/SmCo₅/Cr films were fabricated by using DC facing target magnetron sputtering apparatus at room temperature. The influence of sputtering parameter on their microstructure and magnetic properties were studied, respectively.As for the CoCrTa samples with Ti/Cr underlayers, the experiment results indicate that the Ti underlayer can induce the c-axis orientation of CoCrTa grain in the direction perpendicular to the film surface. The magnetic measurement shows that the c-axis of CoCrTa was not parallel to the film surface. Meanwhile, the diffraction peak of CoCrTa (00.2) was observed in the X-ray diffraction patterns. The optimum substrate temperature (600 ℃) was obtained. Here, the coercivity vertical to the film surface Hc_⊥ was 863.9 Oe, and the squareness vertical to the film surface S_⊥ was 0.33. The proper substrate temperature also favored the decrease of film surface roughness, grain and magnetic domain size. According to the experiment results, the optimum thickness of Ti underlayer was 40 nm, with the value of Hc_⊥ being 1173.7 Oe and thatof 5i being 0.41.The optimum substrate temperature to prepare SmCos/Cr was 450 °C. Here, the film has formed well Cr (110) texture, and the coercivity He was as high as 2141.2 Oe. When the thickness of Cr underlayer was more than 240 nm, a Cr (110) diffraction peak which matched with SmCo (10.1) plane can be distinguished. Accordingly, the coercivity parallel to the film surface of the Cr/SmCos/Cr increased. The proper thickness of Cr underlayer also decreased the surface roughness and grain size. The sputtering pressure has great effect on the microstructure and magnetic properties of Cr/SmCof/Cr films.The magnetic measurement shows that the smple has the largest He (2374.9 Oe), when the sputtering pressure was 2 Pa. Meanwhile, 5M plots indicate that exchange interaction and dipolar interaction were nearly zero at 2 Pa. We also find when the sputtering pressure was higher than 2 Pa, the grain size dramatically increased.