Magnetic Recording Medium Free Layer Thickness Gradient
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic recording media experience a tendency for the free layer to become thicker near the outer periphery than the inner periphery due to the migration phenomenon, leading to potential damage and contamination of the magnetic head, as well as reduced self-repairing effects and increased wear.
Innovation Solution
A magnetic recording medium with a disk-shaped substrate, a magnetic layer, a protective layer, a bonding layer containing a lubricant component, and a free layer that is movable on the bonding layer, where the free layer is thinner near the outer periphery than the inner periphery, and the bonding layer's surface is higher near the outer periphery, reducing the migration of the free layer by centrifugal force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the free layer is made thicker to enhance self-repairing effect, then the ability to fill scratches improves, but the free layer becomes excessively thick near the outer periphery causing magnetic head contamination
Solution Approach 1:
The patent applies local quality by creating a non-uniform free layer thickness distribution where the thickness varies in the radial direction. The free layer is thinner near the outer periphery and thicker near the inner periphery, allowing each region to have optimal thickness for its specific function while preventing magnetic head contamination in the outer recording zone.
Solution Approach 2:
The patent implements preliminary anti-action by pre-configuring the free layer with a thickness gradient before operation. The free layer is designed to be thinner near the outer periphery from the outset, preventing the migration phenomenon from causing excessive thickness buildup that would lead to magnetic head contamination during disk rotation.
2Ease of manufacture
If the free layer thickness is uniform across the disk, then manufacturing is simplified, but the free layer migrates outward causing uneven thickness and head damage
Solution Approach 1:
The patent transitions from uniform thickness to local quality by implementing a radial thickness gradient in the free layer. This allows the free layer to have different thicknesses at different radial positions, optimizing protection against migration-induced head damage while maintaining manufacturability through controlled deposition processes.
Solution Approach 2:
The patent applies dimensionality change by introducing radial variation in the free layer thickness. Instead of maintaining constant thickness in the radial dimension, the free layer thickness becomes a function of radial position, creating a thickness gradient that counteracts the outward migration force during disk rotation.
3Reliability
If the bonding layer is made thicker in the inner zone, then head wear during landing is reduced, but the free layer migrates outward more easily causing outer zone thickening
Solution Approach 1:
The patent applies local quality by creating a coordinated thickness profile where both the bonding layer and free layer have radial variations. The bonding layer is thicker in the inner zone for head wear protection during landing, while the free layer is designed with a thickness gradient that is thinner near the outer periphery, preventing excessive migration-induced thickening in the recording zone.
Solution Approach 2:
The patent implements asymmetry by creating non-uniform thickness distributions in both the bonding layer and free layer across the radial direction. The bonding layer has asymmetric thickness with more material in the inner zone for landing protection, while the free layer has asymmetric thickness gradient to counteract outward migration, resulting in an asymmetric overall lubricating film structure optimized for different operational zones.
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 configuration minimizes the likelihood of the free layer becoming thicker near the outer periphery, reducing wear and damage to the magnetic head, while maintaining the self-repairing effect and ensuring stable information recording and retrieval.
Implementation Method 1
its upper part moves toward the outer periphery (outer side) of the magnetic disk due to centrifugal force generated by the rotation of the magnetic disk
Data Source
AI summary
The present invention provides a magnetic recording medium with a reduced tendency for a free layer to become thicker near an outer periphery than near an inner periphery of a recording zone as well as provides an information reproducing apparatus which is equipped with the magnetic recording medium and reproduces information according to the magnetization at various points on the magnetic recording medium. A magnetic layer carries information in an outer zone outside a predetermined inner zone around a through-hole. That part of the free layer which is located in the outer zone is thinner near the outer periphery than near the inner periphery.