| 摘要 |
A method for manufacturing a substrate for a magnetic disk, including the steps of (a) polishing a substrate with a polishing composition A containing alumina abrasives having an average particle size of from 0.05 to 0.5 μm, and an oxidizing agent, and (b) polishing the substrate with a polishing composition B containing silica particles having an average particle size of from 0.005 to 0.1 μm; a substrate for a magnetic disk, obtainable by the method for manufacturing a substrate for a magnetic disk; and a substrate for a magnetic disk having the following surface properties of a long-wavelength waviness of 0.05 nm or more and 0.3 nm or less, and an AFM surface roughness of 0.03 nm or more and 0.2 nm or less. The substrate for a magnetic disk may be suitably used in the manufacture of a hard disk having a high recording density. Especially, a hard disk having a recording density of 50 G bits or more per square inch may be industrially manufactured. |
