Thermally-Assisted Magnetic Recording Characterization Method
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Solution Overview
Problem
Current thermally-assisted magnetic recording technologies face challenges in evaluating the characterization of magnetic recording devices due to the need for precise consideration of heat-related parameters, particularly in achieving high recording density and signal-to-noise ratio, where the thermal stability of magnetization and magnetic field interactions are critical.
Innovation Solution
A method for evaluating the characterization of thermally-assisted magnetic recording devices involves recording a reference signal, heating specific points on the magnetic recording medium without applying a recording magnetic field, measuring signal intensity, and determining the maximum distance between heating points where the signal intensity is attenuated, allowing for the evaluation of recording density, thermal gradients, and temperature distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnetic grain size is decreased to increase recording density, then recording density is improved, but thermal stability of magnetization deteriorates
Solution Approach 1:
The patent applies parameter changes by heating the magnetic recording medium to temporarily reduce its coercive force (magnetic parameter), enabling recording at higher densities. The heating process changes the thermal state of the medium, allowing magnetization reversal at smaller grain sizes without compromising thermal stability during normal operation.
Solution Approach 2:
The patent utilizes phase transition concepts by heating the magnetic medium to a temperature where its magnetic properties change (reduced coercive force), enabling recording. After cooling, the medium returns to its stable state with restored thermal stability, effectively using a temporary phase change to resolve the contradiction.
2Stability of the object's composition
If magnetic anisotropy energy Ku is increased to improve thermal stability, then thermal stability is improved, but anisotropic magnetic field (coercive force) increases making recording impossible
Solution Approach 1:
The patent changes the temperature parameter of the magnetic recording medium during recording to temporarily reduce the anisotropic magnetic field. By heating the medium, the coercive force is reduced to a level that allows the recording head to write data, while maintaining high Ku for thermal stability during normal operation.
3Quantity of substance
If thermally-assisted magnetic recording is implemented to achieve high recording density, then recording density is improved, but precise evaluation of characterization becomes difficult due to heat-related parameters
Solution Approach 1:
The patent segments the evaluation process into distinct phases: recording evaluation (with thermal assistance) and reproduction evaluation (without thermal assistance). This separation allows precise measurement of different parameters independently, resolving the contradiction between achieving high density and maintaining measurement precision.
Solution Approach 2:
The patent extracts the thermal assistance element from the reproduction evaluation process, using only magnetic field for reading while reserving thermal assistance solely for recording. This extraction enables precise reproduction measurements without heat-related interference while still achieving high recording density during the recording phase.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables precise evaluation of thermally-assisted magnetic recording devices by assessing heat-related parameters, improving recording density and signal quality by optimizing thermal gradients and temperature distributions on the magnetic recording medium.
Implementation Method 1
light propagating through the waveguide couples to the plasmon-generator in a surface plasmon mode so as to excite surface plasmon, and the surface plasmon propagates through the plasmon-generator (propagation edge), so that the near-field light is generated
Implementation Method 2
the near-field light is generated at the near-field light generating portion that is positioned in an air bearing surface side end part of the propagation edge
Implementation Method 3
a magnetic recording medium is heated when the near-field light that is generated in the near-field light generating portion of the plasmon-generator is radiated to the magnetic recording medium
Implementation Method 4
a magnetic field is applied under a state where an isotropic magnetic field of the magnetic recording medium is reduced, and thereby information is recorded
Implementation Method 5
a magnetic field is applied under a state where an isotropic magnetic field of the magnetic recording medium is reduced, and thereby information is recorded
Data Source
AI summary
Using a thermally-assisted magnetic recording device, a reference signal is recorded to a magnetic recording medium. After heating each of first and second heating points, where the first and second heating point being positioned respectively at inner and outer sides along a track width direction with respect to a track width center point of a recording bit where the reference signal is recorded, the reproducing signal intensity of the reference signal is measured. Then, obtaining a maximum distance between the first heating point and the second heating point when a reproducing signal intensity measurement value of the reference signal after the magnetic recording medium is heated is approximately zero. Based on the maximum distance, a characterization of the thermally-assisted magnetic recording device is evaluated.