Magnetic properties of Dy(Tb)Co/Cr thin films for hybrid recording

The magnetic properties of a DyCo layer with and without a Cr underlayer has been investigated. Optimal sputtering conditions of TbCo/Cr films for higher coercivity have been researched. Magnetron sputtering was used here to produce Cr/Dy(Tb)Cox/Cr films on glass substrates. It was found that both the magnetic and the Cr underlayer thickness could influence the coercivity of DyCo films. A coercivity as high as 3,500 Oe was obtained in 255 nm Dy31Co69 films with a 65 nm thick Cr underlayer, but it was only about 2,000 Oe for the same thickness Dy31Co69 films without Cr underlayer. The Cr underlayer thickness was varied in the range 16–330 nm to study its effect on magnetic properties in the films. Under optimal sputtering conditions, a coercivity as high as 6.5 kOe was obtained in TbCo/Cr films. The results indicate that Cr underlayers are suitable for DyCo layers in order to increase the coercivity and the Dy(Tb)Co/Cr film are good candidates for high density recording media.