Interlayer Coupling Field Control in TMR Read Heads
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current magnetic read heads face challenges in reducing magnetic field interlayer coupling (Hint) while maintaining low resistance-area (RA) and high magnetoresistance ratio, which is essential for increasing areal recording densities, as the interlayer coupling field biases the free layer, reducing sensor sensitivity and signal output.
Innovation Solution
Incorporating an interlayer coupling field canceling layer with a cancelling magnetic field pinned anti-parallel to the pinned magnetic structure, along with a spacer layer and control layer, to counteract the interlayer coupling field, allowing for thinner barrier layers without reducing sensitivity, and optimizing the thickness and material of the spacer layer to adjust the magnetic field strength and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the barrier layer thickness is decreased to reduce the RA product and increase magnetoresistance ratio, then the signal-to-noise ratio improves, but the interlayer coupling field increases exponentially causing the free layer to bias in the pinned layer direction, reducing sensor sensitivity
Solution Approach 1:
A nonmagnetic coupling layer is introduced between the pinned magnetic structure and the free magnetic layer. This intermediary layer decouples the magnetic interaction while allowing the thin barrier layer to maintain low RA product and high magnetoresistance ratio, thereby improving signal-to-noise ratio without suffering from excessive interlayer coupling field effects
Solution Approach 2:
The harmful magnetic coupling interaction is extracted and removed by replacing the direct magnetic coupling through the barrier layer with a nonmagnetic coupling layer that eliminates the interlayer coupling field while preserving the electrical tunneling characteristics needed for TMR effect
2Stability of the object's composition
If hard or soft bias layers are increased to provide stabilization field for longitudinal bias state, then the stability improves, but the stiffness of the sensor increases and signal output decreases
Solution Approach 1:
The nonmagnetic coupling layer acts as a mediator that provides the necessary magnetic stabilization for longitudinal bias state while preventing excessive stiffness from transmitting to the sensor structure, thereby maintaining signal output capability
Solution Approach 2:
The thickness and material properties of the nonmagnetic coupling layer are optimized to provide appropriate magnetic stabilization field strength, allowing adjustment of the stabilization parameter to achieve desired bias state stability without excessive sensor stiffness
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 effectively reduces the interlayer coupling field, enhancing the signal-to-noise ratio and sensitivity of the read head, enabling higher areal recording densities without compromising sensor stability.
Implementation Method 1
an interlayer coupling field canceling layer disposed on top of the free layer, wherein the interlayer coupling field canceling layer has a cancelling magnetic field pinned in a direction anti-parallel to the magnetic field of the pinned magnetic structure
Implementation Method 2
the interlayer coupling field biases the free layer in the pinned layer direction
Implementation Method 3
the resistance-area RA product while keeping the magnetoresistance ratio high in a small RA region
Data Source
AI summary
The embodiments generally relate to a read head in a magnetic recording head. The read head utilizes a sensor structure having a pinned magnetic structure with a magnetic field, a barrier layer disposed on top of the pinned magnetic structure, a free layer disposed on top of the barrier layer, and an interlayer coupling field canceling layer disposed on top of the free layer. The interlayer coupling field canceling layer has a cancelling magnetic field pinned anti-parallel the magnetic field of the pinned magnetic structure.