Perpendicular Anisotropy Free Layer Magnetic Sensor Side Shields
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Solution Overview
Problem
As magnetic sensor dimensions decrease, maintaining in-plane anisotropy of magnetic layers becomes challenging, leading to increased noise and instability due to canting of magnetization and external field effects, which reduces signal quality and areal density capabilities in magnetic recording systems.
Innovation Solution
A tunneling magneto-resistive reader design featuring a perpendicular anisotropy free layer and side shields, where a non-magnetic spacer layer separates a reference magnetic element from a free magnetic element, and composite side shields electrically insulate the top and bottom magnetic shields, preventing canting and enhancing stability and signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the dimensions of the magnetic sensor are decreased to increase areal density, then the areal density capability is improved, but the magnetization of the free layer cants away from the anisotropic magnetization direction, increasing noise and reducing signal quality
Solution Approach 1:
The patent changes the magnetization orientation parameter from in-plane to perpendicular anisotropy in the free layer. This parameter change allows the sensor to maintain stable magnetization at smaller dimensions, preventing canting and preserving signal quality while enabling higher areal density.
Solution Approach 2:
The patent transitions the magnetization direction from the in-plane dimension to the perpendicular dimension. By orienting magnetization perpendicular to the film plane rather than within it, the sensor maintains magnetic stability at reduced dimensions, solving the canting problem that limits areal density improvement.
2Productivity
If the dimensions of the magnetic sensor are decreased, then the areal density capability is improved, but thermal variations and external fields cause changes in canting direction, increasing noise and instability
Solution Approach 1:
The patent changes the anisotropy parameter from in-plane to perpendicular orientation in the free layer. This parameter change fundamentally alters the magnetic energy landscape, creating a stable perpendicular magnetization state that is insensitive to thermal variations and external fields, thereby improving magnetization stability at small dimensions.
3Force
If a permanent magnet is employed to bias magnetic layers, then the magnetic layers are biased, but the magnetization direction of the reference layer tilts off-axis, reducing the signal generated by the magnetic sensor
Solution Approach 1:
The patent changes the magnetization orientation parameter of the free layer to perpendicular anisotropy. This parameter change eliminates the need for permanent magnet biasing structures, as the perpendicular anisotropy inherently provides the necessary magnetic field orientation, preventing reference layer tilting and maximizing signal generation.
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 design improves areal density capabilities and reduces noise by maintaining the perpendicular anisotropy of the free layer, thereby enhancing the stability and signal quality of the magnetic sensor, even at smaller dimensions.
Implementation Method 1
A free magnetic element having a free magnetization orientation direction substantially perpendicular to the reference magnetization orientation direction
Implementation Method 2
A non-magnetic spacer layer separates the reference magnetic element from the free magnetic element
Implementation Method 3
The first side magnetic shield and the second side magnetic shield electrically insulates the top magnetic shield from a bottom magnetic shield
Implementation Method 4
A tunneling magneto-resistive reader includes a sensor stack separating a top magnetic shield from a bottom magnetic shield
Data Source
AI summary
A tunneling magneto-resistive reader includes a sensor stack separating a top magnetic shield from a bottom magnetic shield. The sensor stack includes a reference magnetic element having a reference magnetization orientation direction and a free magnetic element having a free magnetization orientation direction substantially perpendicular to the reference magnetization orientation direction. A non-magnetic spacer layer separates the reference magnetic element from the free magnetic element. A first side magnetic shield and a second side magnetic shield is disposed between the top magnetic shield from a bottom magnetic shield, and the sensor stack is between the first side magnetic shield and the second side magnetic shield. The first side magnetic shield and the second side magnetic shield electrically insulates the top magnetic shield from a bottom magnetic shield.