Pt/Co films with thicker Co bottom and top layers improve the magnetic sensitivity of Pt/Co multilayer disks. By increasing the Co bottom and top layer thickness into 7Å in Pt8Å/Co3Å disks, the magnetic sensitivity is improved to an erasing field of -150 Oe and a writing field of 150 Oe, whereas in a conventional disk an erasing field of more than -400 Oe and a writing field of 300 Oe are needed. Carrier level increases because the total Co thickness is larger. Therefore, compared with a conventional Pt/Co disk, 1 dB higher carrier to noise ratio is obtained. Improved Pt/Co disks using thicker Co layers are promising candidates for high density magneto-optical disks using a short wavelength laser and a magnetic field modulation method.