Measurement method of time dependent magnetic remanence in a recording medium
AssigneeFujitsu Limited
InventorsYasuo Bamba, Iwao Okamoto, Kazunori Yamanaka, Wataru Yamagishi
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Abstract
A testing method for a magnetic recording medium which is magnetized measures variation of magnetization with the passage of time and evaluates the magnetic recording medium over its life. The method includes the steps of recording a first pattern at a density to be guaranteed in the magnetic recording medium, the first pattern having a difference between the sum total of areas of +bits and the sum total of areas of -bits, measuring remanence of the first pattern with the passage of time, and evaluating the magnetic recording medium over its life based on a measurement result.
Claims10
A testing method of a magnetic recording medium which is magnetized, for measuring variation of magnetization with the passage of time and evaluating life of record on said magnetic recording medium, said method comprising the steps of:
- (a) recording a first pattern at a linear density to be guaranteed in said magnetic recording medium, said first pattern having a difference between the sum total of areas of +bits and the sum total of areas of -bits;
- (b) measuring remanence of said first pattern with the passage of time;
- and
- (c) evaluating the life of record on said magnetic recording medium based on a measurement result obtained in step (b).
A testing method of a magnetic recording medium which is magnetized, for measuring variation of magnetization with the passage of time and evaluating life of record on said magnetic recording medium, said method comprising the steps of:
- (a) recording a first pattern and a second pattern in said magnetic recording medium, said first pattern having a difference between the sum total of areas of +bits and the sum total of areas of -bits, said second pattern having a uniform magnetization;
- (b) measuring remanence of said first and second patterns with the passage of time;
- and
- (c) evaluating the life of record on said magnetic recording medium based on measurement results of the remanence of said first and second patterns obtained in step (b).
A method of measurement of a time constant of magnetization reversal in a magnetized sample, comprising the steps of:
- (a) measuring a time-dependent remanence of a bit pattern of the magnetized sample, so that a group of measurement points each of which is defined by a measured residual magnetic moment and a measurement time point are obtained, the group of measurement points indicating a transient tendency of magnetic relaxation of the bit pattern of the magnetized sample;
- (b) obtaining a characteristic of transient response to the remanence based on the group of measurement points obtained in said step (a);
- and
- (c) obtaining a time constant of magnetization reversal based on the characteristic of transient response of the remanence obtained in said step (b).
Dependencies are inferred from the claim text.