Polishing liquid and polishing method

1. A polishing slurry, comprising:

a colloidal silica having an average particle size of 40 nm or more;

water; and

a ζ potential adjusting component,

wherein:

the ζ potential adjusting component comprises

at least one water-soluble organic polymer selected from the group consisting of a water-soluble polyether polyamine and a water-soluble polyalkylene polyamine, and

at least one acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, nitrous acid and amidosulfuric acid;

the ζ potential adjusting component contains the acid at a ratio of from 0.6 to 1.4 to the water-soluble organic polymer in terms of molar ratio; and

the polishing slurry has a pH of 8 or more.

2. The polishing slurry according to claim 1 , wherein a content of the water-soluble organic polymer is from 0.0001 to 0.5 mol/L.

3. The polishing slurry according to claim 1 , wherein the colloidal silica has an average particle size of from 100 nm or less.

4. The polishing slurry according to claim 1 , wherein the polishing slurry has a pH of from 9 to 10.

5. A polishing method, comprising polishing an object to be polished, with the polishing slurry according to claim 1 .

6. The polishing method according to claim 5 , further comprising, during the polishing, adjusting a ζ potential of a surface of the object to be polished to −90 mV or more.

7. The polishing method according to claim 5 , wherein the object to be polished comprises silicate glass, quartz glass or quartz, or a surface to be polished of the object to be polished comprises silicic acid or a silicate.

8. A method for manufacturing a glass substrate for a magnetic disk, said method comprising the polishing method according to claim 5 .