Perpendicular Magnetic Recording Medium Underlayer Grain Shape
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for manufacturing perpendicular magnetic recording media face challenges in minimizing magnetic cluster size, reducing intergranular interaction, and achieving high recording density while maintaining thermal stability and low noise, as existing underlayer structures either complicate the manufacturing process or fail to simultaneously satisfy the conditions of increasing grain density, suppressing superparamagnetic grains, and reducing orientation dispersion.
Innovation Solution
A perpendicular magnetic recording medium with an underlayer composed of crystal grains and an amorphous grain boundary, where the crystal grains have a shape with a larger bottom region area than top region area, and a magnetic recording layer with ferromagnetic grains surrounded by a nonmagnetic material, achieving a favorable segregation structure and improved crystallinity, which reduces magnetic cluster size and orientation dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the magnetic grain diameter is minimized to reduce magnetic cluster size and intergranular interaction, then noise is reduced and recording density is improved, but the magnetic grains transform to a superparamagnetic state and lose ferromagnetic property when the grain diameter becomes smaller than 4 nm
Solution Approach 1:
The patent applies local quality by creating a segregated structure where nonmagnetic chromium is concentrated specifically at the grain boundaries while maintaining appropriate concentration within the crystal grains. This local differentiation allows the grain interior to maintain ferromagnetic properties while the grain boundaries provide magnetic isolation, achieving both small magnetic cluster size and stable ferromagnetic behavior.
Solution Approach 2:
The patent segments the magnetic recording layer into distinct crystal grains with nonmagnetic chromium-rich boundaries separating them. This segmentation creates isolated magnetic clusters that prevent intergranular interaction while maintaining individual grain ferromagnetic properties, effectively dividing the magnetic structure to achieve both small cluster size and thermal stability.
2Reliability
If a soft magnetic backing layer is added to concentrate magnetic flux and improve recording performance, then medium performance is enhanced, but the device complexity and manufacturing process are complicated
Solution Approach 1:
The patent extracts or removes the soft magnetic backing layer from the conventional perpendicular magnetic recording medium structure. By eliminating this layer while optimizing the magnetic recording layer itself with a segregated structure, the invention achieves simplified device architecture while maintaining recording capability through the improved grain boundary segregation that concentrates magnetic properties where needed.
3Ease of manufacture
If conventional continuous film magnetic recording layers are used, then manufacturing is simpler, but the intergranular interaction cannot be effectively reduced and magnetic cluster size remains large
Solution Approach 1:
The patent changes the compositional parameters of the magnetic recording layer by introducing a segregated structure with varying chromium concentration - higher at grain boundaries and lower within crystal grains. This parameter change transforms the uniform continuous film into a heterogeneous structure with distinct phases, achieving small magnetic cluster size while maintaining compatibility with conventional deposition processes.
Solution Approach 2:
The patent creates a composite magnetic recording layer consisting of ferromagnetic crystal grains embedded in a nonmagnetic chromium-rich grain boundary phase. This composite structure combines magnetic and nonmagnetic materials at the nanoscale, achieving effective magnetic isolation and small cluster size while being manufacturable using standard thin film deposition techniques.
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 approach results in improved recording density, reduced noise, enhanced thermal stability, and increased signal-to-noise ratio (SNR) by minimizing magnetic cluster size and maintaining high crystallinity, thus overcoming the limitations of previous underlayer structures.
Implementation Method 1
an underlayer for aligning the magnetic recording layer in the desired direction
Implementation Method 2
The underlayer is composed of crystal grains and an amorphous grain boundary
Implementation Method 3
the formation of a segregation structure has been proposed in which a CoCr alloy is used and the concentration of nonmagnetic chromium in the grain boundary is at least 1.4 times the concentration in the crystal grains
Implementation Method 4
the magnetic recording layer comprises ferromagnetic crystal grains and a nonmagnetic material surrounding the ferromagnetic crystal grains
Data Source
AI summary
A perpendicular medium is disclosed in which an isolation structure of an underlayer is formed using a simple method as in a conventional manufacturing process for a medium of continuous films. The method suppresses dispersion of alignment and reduced magnetic cluster size in a magnetic recording layer. The perpendicular medium exhibits high recording density owing to thin film thickness of the underlayer. A perpendicular magnetic recording medium includes at least an underlayer and a magnetic recording layer sequentially laminated on a nonmagnetic substrate. The underlayer consists of crystal grains and an amorphous grain boundary, and the crystal grain has a shape holding a relation (an area of a bottom region at an initial stage of growth)>(an area of a top region).