Magnetic Recording Medium Grain Diameter Control
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Solution Overview
Problem
Current magnetic recording technologies face challenges in achieving high recording density and signal-to-noise ratio due to irregular magnetization transitions and grain coupling, leading to unclear write-bit boundaries and decreased electromagnetic conversion characteristics.
Innovation Solution
A magnetic recording medium is developed with a perpendicular magnetic recording layer comprising magnetic grains surrounded by a nonmagnetic substance, where the variation in the ratio of long to short diameter and grain diameter of the grains is controlled within specific ranges to minimize grain coupling and optimize grain separation, using a nonmagnetic substance with a higher density to prevent diffusion and enhance coercive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnetic grains are miniaturized to increase recording density, then recording density is improved, but grain coupling increases and magnetization transitions become irregular
Solution Approach 1:
The patent introduces a nonmagnetic substance specifically at the grain boundaries to create localized isolation zones. This local modification prevents magnetic coupling between adjacent grains without affecting the overall miniaturization strategy, thereby maintaining regular magnetization transitions while increasing recording density.
Solution Approach 2:
The nonmagnetic substance acts as an intermediary barrier between magnetic grains. It physically separates the magnetic moments of adjacent grains, preventing their coupling and ensuring that each grain magnetizes independently, thus maintaining transition regularity despite grain miniaturization.
2Reliability
If grain separation is increased to reduce coupling, then magnetization transition regularity is improved, but recording density decreases
Solution Approach 1:
Instead of uniformly increasing grain separation throughout the entire magnetic layer, the patent concentrates the nonmagnetic substance specifically at grain boundaries. This localized approach provides sufficient separation to prevent coupling while maintaining high overall grain density and recording capacity.
Solution Approach 2:
The nonmagnetic substance creates a porous or nonmagnetic network at grain boundaries that acts as a spacing mechanism. This structure provides the necessary separation between magnetic grains to ensure regular magnetization transitions while allowing the overall grain density to remain high for maximum recording density.
3Reliability
If nonmagnetic substance content is increased to improve grain isolation, then magnetization transition regularity is improved, but coercive force decreases
Solution Approach 1:
The nonmagnetic substance is placed locally only where it is needed - at grain boundaries - rather than being distributed throughout the entire magnetic layer. This localized placement provides sufficient isolation to ensure regular magnetization transitions while minimizing the overall nonmagnetic content to preserve the coercive force of the magnetic grains.
Solution Approach 2:
The patent optimizes the concentration and distribution parameters of the nonmagnetic substance to achieve the desired balance. By carefully controlling the amount and placement of the nonmagnetic material, the patent achieves sufficient grain isolation without excessively reducing the magnetic content that provides coercive force.
Data Source
AI summary
In order to provide a magnetic recording medium having excellent electromagnetic conversion characteristics, a magnetic recording medium (10) is provided with a substrate (12), and a magnetic recording layer (20) formed on the substrate (12). The magnetic recording layer (20) is provided with a granular layer (32), i.e., a magnetic layer, including magnetic grains and a nonmagnetic material surrounding the magnetic grains in a section parallel to the main surface of the substrate. The ratio of the long diameter to the short diameter of each magnetic grain contained in the granular layer (32) is calculated in the section. In the histogram of such ratio, a half width at half maximum of the histogram is 0.6 or less and the variance of grain diameters of the magnetic grains in the section is 20% or less of the average grain diameter of the magnetic grains.