Magnetic recording medium

DETAILED DESCRIPTION In addition to regions where ordinary information is recorded, the magnetic recording medium in the hard disk drive must have regions for recording servo information for tracking by the magnetic head.
However, it was not discussed in the prior art how to record servo information in a patterned medium of the perpendicular recording type.
The inventors have reached the conclusion that in a patterned medium, like data recording, servo information may be recorded in minute recording portions (to be referred to as unit minute recording portions, hereinafter).
In that event, however, there arises a problem that servo information can be inadvertently rewritten or erased when data are recorded or erased.
An object of the invention is to prevent inadvertent rewriting or erasure of servo information in a patterned medium based on the perpendicular recording mode.
This and other objects are attained by the present invention which is defined below as (1) to (6).
(1) A magnetic recording medium for use in magnetic write/read operation by the perpendicular recording mode, comprising recording tracks each having an array of unit minute recording portions of a magnetic material separated by non-recording portions of a nonmagnetic material, each unit minute recording portion having a surface area and a thickness, wherein the recording tracks include data regions and servo regions, the unit minute recording portions in the data regions have substantially the same surface area as the unit minute recording portions in the servo regions, and AR.
sub.
S /AR.
sub.
D.
gtoreq.
1.
5 provided that the unit minute recording portion has an aspect ratio which is the thickness divided by the square root of the surface area thereof, the unit minute recording portion in the data region has an aspect ratio AR.
sub.
D, and the unit minute recording portion in the servo region has an aspect ratio AR.
sub.
S.
(2) The magnetic recording medium of (1) wherein AR.
sub.
S /AR.
sub.
D.
ltoreq.
10.
(3) The magnetic recording medium of (1) wherein AR