Zn-Based Intermediate Layer for Perpendicular Magnetic Recording Media
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Solution Overview
Problem
Perpendicular magnetic recording media face challenges in achieving high-density recording with magnetic characteristics comparable to Ru or Re while using inexpensive materials, as existing substitutes like Ge, Cu, Ni, Au, Pd, or Re-based intermediate layers often result in increased media noise due to reduced magnetic layer thickness and orientation issues.
Innovation Solution
The use of an intermediate layer with a hexagonal close-packed (hcp) structure containing 55% or more Zn, combined with a magnetic layer having an hcp structure with Co and a Δθ50 value between 1.5° and 4°, along with additional elements like Ta, Mo, Mg, Au, Ti, Ag, Dy, Nb, Cr, V, B, and Si, to suppress disorder in crystal orientation and reduce media noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ru or Re is used in the intermediate layer, then magnetic characteristics are improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent replaces expensive Ru or Re intermediate layers with inexpensive Zn-based intermediate layers containing 55 at% or more Zn. This substitution dramatically reduces manufacturing cost while maintaining the necessary magnetic characteristics through proper compositional control and crystal structure engineering.
Solution Approach 2:
The patent changes the compositional parameters of the intermediate layer from Ru/Re-based to Zn-based with specific content ranges (55 at% or more Zn). It also controls the magnetic layer thickness and composition parameters to achieve optimal magnetic characteristics without relying on expensive materials, thereby resolving the cost-performance contradiction.
2Quantity of substance
If magnetic layer thickness is reduced to increase recording density, then recording density improves, but media noise increases due to orientation degradation
Solution Approach 1:
The Zn-based intermediate layer serves as a mediator between the substrate and the thin magnetic layer. It provides strong orientation control that maintains crystal alignment even when the magnetic layer thickness is reduced to 10 nm or less, thereby enabling high recording density while suppressing media noise through proper intermediate layer design.
Solution Approach 2:
The patent controls the thickness of the magnetic layer within specific ranges (5-20 nm) and adjusts the compositional parameters of the Zn-based intermediate layer to maintain optimal orientation. This parameter optimization allows thin magnetic layers to achieve high recording density without suffering from orientation degradation and associated media noise.
3Ease of manufacture
If Zn-based intermediate layer is used instead of Ru or Re, then manufacturing cost decreases, but magnetic characteristics may deteriorate
Solution Approach 1:
The patent systematically optimizes the compositional parameters of the Zn-based intermediate layer, specifying 55 at% or more Zn content, and controls the magnetic layer composition and thickness parameters. These parameter optimizations ensure that the inexpensive Zn-based intermediate layer achieves magnetic characteristics comparable to or better than Ru or Re-based layers.
Solution Approach 2:
The patent creates a composite structure with the Zn-based intermediate layer and Co-based magnetic layer, where the intermediate layer contains specific elements (such as Pt, Pd, Rh, Ir, Ru, Os, Ga, Ge, In, Sn, Sb, Te, Po, Bi, or their combinations) to enhance interfacial properties. This composite approach maintains excellent magnetic characteristics while using inexpensive materials.
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 enables the production of perpendicular magnetic recording media with reduced manufacturing costs and improved magnetic characteristics, including lower media noise and enhanced recording density, without relying on expensive materials like Ru or Re.
Implementation Method 1
the intermediate layer comprises an alloy with the hcp structure containing 55 at % or more Zn, and in which the magnetic layer comprises an alloy with the hcp structure containing Co and has a Δθ50 value for the orientation plane (0002) of between 1.5° and 4°
Data Source
AI summary
A perpendicular magnetic recording media is disclosed which employs inexpensive materials in the intermediate layer of the high-recording density media while exhibiting magnetic characteristics comparable or superior to those of media using Ru or Re. A perpendicular magnetic recording apparatus employing this perpendicular magnetic recording media also is disclosed. The perpendicular magnetic recording media has a nonmagnetic substrate, a soft magnetic backing layer formed on the nonmagnetic substrate, a seed layer formed on the soft magnetic backing layer, an intermediate layer formed on the seed layer, a magnetic layer formed on the intermediate layer, and a protective layer formed on the magnetic layer. The intermediate layer comprises an alloy with the hcp structure containing 55 at % or more Zn, the magnetic layer comprises an alloy with the hcp structure containing Co, and the Δθ50 value of the orientation plane (0002) of the magnetic layer is between 1.5° and 4°.