Magnetic Sensor Non-Rectangular Geometry Stabilizes Micromagnetic State
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Solution Overview
Problem
Magnetoresistive read sensors face challenges with increasing noise levels, particularly shot noise, Johnson noise, thermal magnetic noise, and residual thermal noise (RTN), as the sensor area decreases, affecting signal-to-noise ratio and playback amplitude.
Innovation Solution
The use of non-rectangular shaped sensor stacks and magnetic bias elements, such as trapezoidal or parallelogram geometries, stabilizes either the 'C' or 'S' micromagnetic state, minimizing RTN noise and maintaining a small footprint, while increasing the reader area and reducing electronic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sensor area is decreased to increase recording density, then recording capacity is improved, but noise levels increase and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies asymmetry by using non-rectangular sensor geometries (trapezoidal or parallelogram shapes) instead of conventional rectangular sensors. This asymmetric design stabilizes the micromagnetic state (either C or S state) within the sensor structure, thereby minimizing residual thermal noise (RTN) while maintaining reduced sensor area for high-density recording
2Quantity of substance
If sensor area is decreased to increase recording density, then recording capacity is improved, but playback amplitude decreases
Solution Approach 1:
The non-rectangular sensor geometry creates an asymmetric magnetic field distribution that enhances the playback signal amplitude. The trapezoidal or parallelogram shape concentrates the magnetic flux in a way that maintains stronger signal output despite the reduced sensor area, thus preserving playback amplitude while enabling higher recording density
3Ease of manufacture
If rectangular sensor geometry is used, then fabrication is simple, but noise levels are higher and performance is limited
Solution Approach 1:
The patent transitions from symmetric rectangular geometry to asymmetric non-rectangular geometry (trapezoidal or parallelogram). This asymmetric design, while slightly more complex to fabricate, dramatically reduces residual thermal noise by stabilizing the micromagnetic state, thereby improving sensor performance and signal-to-noise ratio
4Object-affected harmful factors
If non-rectangular geometry is used, then noise levels are reduced and playback amplitude is enhanced, but device complexity increases
Solution Approach 1:
The asymmetric non-rectangular geometry (trapezoidal or parallelogram) is designed to stabilize the micromagnetic state and reduce noise. The complexity is managed by maintaining regular geometric patterns that can be integrated into existing manufacturing processes, balancing performance improvement with fabrication feasibility
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 reduces noise levels and enhances playback amplitude, maintaining signal integrity with a smaller sensor footprint, without increasing the reader width distribution, and allows for easier fabrication.
Implementation Method 1
magnetic bias elements positioned adjacent each side of the sensor stack
Implementation Method 2
magnetic bias elements positioned adjacent each side of the sensor stack
Implementation Method 3
Magnetoresistive read sensors face challenges
Data Source
AI summary
Various embodiments generally relate to a magnetic sensor, and more specifically to a magnetoresistive read head sensor. In one such exemplary embodiment, a magnetic sensor comprises a sensor stack and magnetic bias elements positioned adjacent opposite sides of the sensor stack. At least one of the bias elements has a non-rectangular shape, such as substantially trapezoidal or parallelogram shapes having non-perpendicular corners.