MAGNETIC DISK AND SUBSTRATE FOR MAGNETIC DISK

摘要

PROBLEM TO BE SOLVED: To improve floating stability by providing a magnetic disk with many projecting parts projecting from a front surface at a height larger than the surface roughness of the front surface, arranging these projecting parts spirally with respect to the center of the magnetic disk within specific heights and distributions and confining the offsets in the radial direction between the adjacent projecting parts to the width in the radial direction of the projecting parts or below. SOLUTION: The height of the projecting parts is confined to >=5 to <=40 nm and the projecting parts are preferably formed so as to have the specified height of the distribution within 30% of the average height. The projecting parts formed on a surface protective layer are preferably discontinuous on the same circumference of a magnetic recording medium. At least a part of the portions having no projections is preferably gently continuous from the inner periphery to the outer periphery of the magnetic recording medium within the moving region of a magnetic head. An NiP ground surface film 2 is formed at a thickness of 15μm on the front surface of an alloy disk 1 of aluminum and a Cr intermediate layer 3 is formed at a thickness of 0.2μm, a Co-Ni magnetic layer 4 at a thickness of 40 nm and a C protective layer 5 at a thickness of 20 nm on this substrate. The projecting parts are formed by a photomask on the front surface of the protective layer 5.