Effect of underlayer thickness on magnetic properties of SmCo film

It is well known that the Cr underlayer plays significant role in the magne tic properties of Co alloy film. In this study, the effects of the underlay er materials such as Cr, Mo, W, W/Cr, and Al and their thickness on the mag netic properties of SmCo films were studied. In the x-ray diffraction diagr ams of the SmCo/Cr film and the SmCo/Mo film, only (110) line of body-cente red-cubic crystal structure was observed, while diffraction lines from SmCo phase could not be observed. The oval shaped grains were observed on the s urface of Cr underlayer and the Mo underlayer when the thickness was thicke r than 100 nm. The coercivity of the SmCo/Cr film and the SmCo/Mo film with thickness over 100 nm was higher than 3 kOe and the squareness ratio and t he coercivity squareness ratio was above 0.8 and 0.9, respectively. These r esults indicate the Cr underlayer and the Mo underlayer are suitable for Sm Co layers in order to increase the coercivity and the SmCo/Cr film and the SmCo/Mo film are good candidates for high density recording media. (C) 2000 American Institute of Physics. [S0021-8979(00)47008-8].