Patent ID: 7037607

Claim:
A magnetic recording medium having a center of rotation and comprising a substrate, a magnetic film layer formed thereon and a protective film layer formed thereon for the protection of said magnetic film layer and composed mainly of carbon, said medium having a Contact-Start-And-Stop (CSS) area and a data area, said CSS area located closer to said center of rotation than said data area, wherein a thickness A of said protective film layer in said CSS area is larger than a thickness B of said protective film layer in said data area, said protective film layer in said CSS area comprises, an upper film and a lower film, and said protective film layer comprises a boundary having a specific steepness in the film thickness between said CSS area and said data area, (R 2 −R 1 )<5 mm where R 1 is a radial position measured from said center of rotation to the end of the boundary in the direction of a thickness decrease which corresponds to 90% of the thickness A and R 2 is a radial position measured from said center of rotation to the end of the boundary in the direction of a thickness increase which corresponds to 110% of the thickness B, an A/B ratio is 1.3 or more, said upper film of said protective film layer in said CSS area and said protective film layer in said data area are amorphous carbon layers, said amorphous carbon layers being composed mainly of carbon, a combination of carbon and nitrogen, or a combination of carbon, nitrogen and hydrogen, wherein said lower film is a Diamond-Like Carbon (DLC) layer being mainly composed of carbon and hydrogen.