Patent ID: 6541132
Filing Date: 2003-04-01
Classification: G11B

Abstract:
A magnetic disk comprising:a support; a non-magnetic layer which is substantially non-magnetic; and a magnetic layer having a thickness of less than 0.15 &mgr;m and containing as ferromagnetic powder, at least one of fine particles of ferromagnetic metal and ferromagnetic hexagonal ferrite dispersed in a binder, in this order, wherein (I) the disk has a track width of less than 5 &mgr;m and is able to record signals having a bit length of less than 0.5 &mgr;m, (II)-(i) when the ferromagnetic powder is fine particles of ferromagnetic metal, the fine particles of ferromagnetic metal have an average major axis length satisfying conditions that a ratio of the track width to the average major axis length is from 50 to 100 and a ratio of the bit length to the average major axis length is from 3 to 20, (II)-(ii) when the ferromagnetic powder is fine particles of ferromagnetic hexagonal ferrite, the fine particles of ferromagnetic hexagonal ferrite have an average tabular diameter satisfying conditions that a ratio of the track width to the average tabular diameter is from 50 to 100 and a ratio of the bit length to the average tabular diameter is from 3 to 20, and (III) the thickness of the magnetic layer has a variation coefficient of 0.5 or below, expressed in terms of a ratio of the standard deviation to the average thickness of the magnetic layer.