Patent ID: 8773958
Filing Date: 2014-07-08
Classification: G01R

Abstract:
1. An estimation method for estimating a distribution width of Curie temperatures of a plurality of magnetic grains that form a magnetic recording layer of a magnetic recording medium used in thermally-assisted magnetic recording, comprising: a heating step in which a recording bit, on which a reference signal is recorded, is heated under each of a plurality of heating conditions having different heating temperatures, the recording bit being at least one recording bit in the magnetic recording medium; a measurement step in which a signal intensity with respect to the reference signal recorded in the recording bit after heating is measured under each of the heating conditions of the heating step; a determining step in which, using the signal intensity with respect to the reference signal measured in the measurement step for each of the different heating temperatures, the lowest Curie temperature of the plurality of magnetic grains, which is the heating temperature when the signal intensity with respect to the reference signal begins to decrease, and the highest Curie temperature of the plurality of magnetic grains, which is the heating temperature when the signal intensity with respect to the reference signal substantially becomes zero, are determined; and a calculation step, in which the difference of the highest Curie temperature and the lowest Curie temperature is calculated, by a computer, as the distribution width of Curie temperatures of the plurality of magnetic grains that form the magnetic recording layer.