Patterned Perpendicular Magnetic Recording Medium With Exchange-Coupled Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Patterned perpendicular magnetic recording media face challenges in achieving uniform data islands with improved magnetic recording properties, including wide switching field distribution and reduced writability due to variations in island size, shape, and magnetic material properties, which are exacerbated by the etching process.
Innovation Solution
A patterned perpendicular magnetic recording medium is developed with first and second ferromagnetic layers (MAG1 and MAG2) separated by nonmagnetic interlayers (IL1 and IL2), along with an optional barrier layer to protect underlying layers during etching, allowing for strong exchange coupling and independent control of microstructure and magnetic properties, resulting in reduced switching field distribution and improved writability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single magnetic recording layer is used in patterned media, then the manufacturing process is simpler, but the writability and switching field distribution are insufficient
Solution Approach 1:
The magnetic recording layer is segmented into multiple sub-layers (first ferromagnetic layer and second ferromagnetic layer) with different magnetic properties. This segmentation allows each layer to contribute differently to the recording process, with the first layer providing thermal stability and the second layer enhancing writability, thereby resolving the contradiction between manufacturing simplicity and recording performance.
Solution Approach 2:
The patent employs a composite magnetic structure consisting of two ferromagnetic layers with distinct characteristics (different coercivities and anisotropies) coupled through nonmagnetic interlayers. This composite approach combines the advantages of high-stability materials with high-writability materials, achieving both reliable thermal storage and improved writability that a single material cannot provide.
2Stability of the object's composition
If the magnetic recording layer is made with high anisotropy for thermal stability, then data retention is improved, but writability deteriorates due to higher switching fields
Solution Approach 1:
The magnetic recording system is divided into two functional layers: the first ferromagnetic layer with high anisotropy provides thermal stability and data retention, while the second ferromagnetic layer with lower coercivity provides writability. This segmentation allows each layer to optimize its function without compromise.
Solution Approach 2:
Different regions of the magnetic recording structure have different magnetic properties tailored to specific functions. The first layer has high anisotropy for stability, while the second layer has softer magnetic properties for writing. This local differentiation of magnetic qualities enables simultaneous achievement of thermal stability and writability.
3Ease of manufacture
If conventional etching processes are used to form data islands, then manufacturing is simpler, but uniformity of island size and shape deteriorates
Solution Approach 1:
A protective barrier layer is deposited on the magnetic recording layers before the etching process. This preliminary protective action prevents the etching process from damaging the magnetic layers, thereby maintaining uniform island dimensions and shapes while still allowing the etch to define the island patterns. The barrier layer is later removed selectively.
Solution Approach 2:
The barrier layer acts as an intermediary between the etching process and the magnetic recording layers. It mediates the interaction by providing a sacrificial layer that protects the sensitive magnetic materials from direct exposure to the etchant, thus preserving the precision of island formation while allowing conventional etching methods to be used.
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
The solution achieves significantly reduced switching field distribution, improved writability, and higher magnetic homogeneity of data islands, enhancing the overall performance of patterned magnetic recording media.
Implementation Method 1
first and second nonmagnetic interlayers (IL1 and IL2) between MAG1 and MAG2... assure that MAG1 and MAG2 are strongly exchange coupled
Data Source
AI summary
A patterned perpendicular magnetic recording medium has discrete data islands that have first and second ferromagnetic layers (MAG1 and MAG2) with first and second nonmagnetic interlayers (IL1 and IL2) between MAG1 and MAG2. MAG1 and MAG2 may be similar CoPtCr alloys with similar thicknesses, with thicknesses of IL1 and IL2 that assure that MAG1 and MAG2 are strongly exchange coupled. Alternatively, MAG2 may be a “write assist” layer, for example a high-saturation magnetization, magnetically soft material in an exchange-spring structure, with IL1 being very thin so that IL2 functions as the coupling layer between MAG1 and the write-assist MAG2 layer. In an application for thermally-assisted recording (TAR), MAG2 may be the chemically-ordered equiatomic binary alloy FePt or CoPt based on the L10 phase, with high magneto-crystalline anisotropy (Ku).