Patent ID: 8748017

Claim:
A bit patterned medium comprising: a substrate; and a magnetic recording layer positioned above the substrate and provided a servo region and a data region, wherein the servo region comprises first protrusion patterns each having a length of 1 μm or more in a radial direction of the medium, the data region comprises one or more of second protrusion patterns each having a length in the radial direction shorter than the length of the first protrusion patterns in the radial direction, each of the first and the second protrusion patterns comprises a plurality of crystal grains, an average distance between the crystal grains being 0.5 to 3.0 nm, magnetic portions are respectively stacked on the crystal grains in each of the first and the second protrusion patterns, wherein an average distance between the magnetic portions on one of the first and the second protrusion patterns is less than the average distance between the crystal grains, and a nucleation field Hn for magnetization reversal and a coercive force Hc in each of the first protrusion patterns satisfy the following inequalities; Hn≧ 1.5 kOe and 0.5 kOe≦ Hc−Hn≦ 1.5 kOe.