KERR ENHANCEMENT BY LAYER MODULATION IN CO PT MULTILAYERS/

Thus far, a good Kerr hysteresis loop has been obtained only for thick ness ratios of Co to Pt lower than 0.6 in Co/Pt multilayers. It has be en found in this study that perfect squareness can be obtained for ult rathin films even with a high thickness ratio of t(Co)/t(Pt) = 1. This is caused by diminished magnetostatic energy. Furthermore, layer-modu lated structures were investigated in order to increase the Kerr rotat ion angle. The Co/Pt multilayers were prepared by two-source rf-magnet ron sputtering. Co/Pt multilayers with perfect squareness were deposit ed with a Pt interlayer, which resulted in excellent magneto-optical p roperties. In particular, the Kerr rotation angle measured from the gl ass-substrate side showed a very large value, 0.73 degrees. This Kerr enhancement is due to optical interference and multiple reflection. On the other hand, another interesting phenomenon was also obtained. Ker r hysteresis showed characteristic stepwise hysteresis loops when the interlayer Pt thickness was increased. Such layer-modulated multilayer s have potentiality for high-density magneto-optical recording.