CPP TMR Read Sensor Dual Seed Cap Layers
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Solution Overview
Problem
Current CPP TMR and GMR read sensors face challenges in achieving high-resolution magnetic recording due to limitations in reducing the read gap and track width, which are essential for increasing linear and track densities.
Innovation Solution
The implementation of dual seed and cap layers, specifically using nonmagnetic Pt and Ru films, minimizes moment losses and enhances thermal and pinning properties, allowing for a narrower read gap and improved ferromagnetic decoupling, thereby facilitating high-resolution magnetic recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the read gap and track width are reduced to increase linear and track densities, then storage capacity is improved, but moment losses increase and thermal stability deteriorates
Solution Approach 1:
The patent employs dual seed layers and dual cap layers composed of different nonmagnetic materials (Pt, Ru, Ta) to create a composite structure. This composite approach allows optimization of both thermal stability and moment loss characteristics, as different materials contribute different properties to the overall sensor structure, enabling high-density recording while maintaining reliability
Solution Approach 2:
The nonmagnetic seed and cap layers serve as intermediary layers between the ferromagnetic layers. These intermediary layers minimize unwanted magnetic interactions and moment losses at interfaces while providing thermal stability, thus enabling the read gap to be reduced without sacrificing reliability
2Measurement precision
If the read gap is narrowed to improve resolution, then measurement precision is improved, but moment losses increase
Solution Approach 1:
The nonmagnetic seed and cap layers act as intermediary barriers that prevent magnetic moment diffusion and loss at the interfaces of the narrow read gap structure, enabling high resolution without excessive moment losses
Solution Approach 2:
The combination of different nonmagnetic materials in the dual seed and cap layers creates a composite structure that optimizes interface properties to minimize moment losses while maintaining the narrow geometry required for high resolution
3Productivity
If the read sensor is miniaturized to increase densities, then productivity is improved, but device complexity increases
Solution Approach 1:
The read sensor is segmented into multiple functional layers including dual seed layers, ferromagnetic layers, dual cap layers, and shield layers. This segmentation allows each layer to be optimized independently for its specific function while collectively achieving high-density recording capability
Solution Approach 2:
The patent transitions from a single-layer structure to a multi-layer vertical structure, utilizing the vertical dimension to accommodate multiple functional layers within a compact footprint, thereby increasing recording density without excessive complexity
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 use of dual seed and cap layers results in minimal moment losses, enabling a narrower read gap and improved magnetic recording capabilities, enhancing the sensitivity and thermal stability of the CPP TMR or GMR read sensor.
Implementation Method 1
the conduction electrons are scattered at lower and upper interfaces of the barrier or spacer layer
Implementation Method 2
A current-perpendicular-to-plane (CPP) tunneling magnetoresistance (TMR) or giant magnetoresistance (GMR) read sensor
Implementation Method 3
A current-perpendicular-to-plane (CPP) tunneling magnetoresistance (TMR) or giant magnetoresistance (GMR) read sensor
Implementation Method 4
Changes in the resistance of the read sensor are detected by a sense current passing through the read sensor, and are then converted into voltage changes
Data Source
AI summary
A current-perpendicular-to-plane (CPP) tunneling magnetoresistance (TMR) or giant magnetoresistance (GMR) read sensor with dual seed and cap layers for high-resolution magnetic recording is provided by the invention. The dual seed layers comprise a lower seed layer preferably formed of a nonmagnetic Pt film and an upper seed layer preferably formed of a nonmagnetic Ru film. The lower seed layer separates the upper seed layer from a buffer layer preferably formed of a ferromagnetic Co—Hf film, in order to minimize moment losses at its lower interface and thus define a sharp lower bound of a read gap. In addition, the lower seed layer facilitates the CPP read sensor to exhibit high pinning properties, while the upper seed layer facilitates the CPP read sensor to exhibit robust thermal properties.