Stepped Tri-Layer Magnetic Sensor for Magnetization Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic field detecting elements with tri-layer stacks face challenges in maintaining consistent magnetization directions without a bias magnetic field, leading to variable detection performance and reduced productivity due to the lack of control over magnetization orientations, especially when multiple elements are produced.
Innovation Solution
A magnetic field detecting element with a tri-layer structure featuring upper and lower magnetic layers, a non-magnetic intermediate layer, and insulating layers with a stepped portion to control magnetization directions through shape magnetic anisotropy, ensuring the upper magnetic layer is shorter than the lower magnetic layer in the track width direction, allowing for antiferromagnetic coupling and desired magnetization states even without a bias magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a tri-layer stack structure is used to simplify the layer structure and reduce layer thickness, then the device complexity is reduced and manufacturing ease is improved, but the magnetization direction control becomes unstable and detection precision deteriorates
Solution Approach 1:
The patent applies local quality by creating an asymmetric structure where the lower magnetic layer has a larger area than the upper magnetic layer in the track width direction. This local area difference generates shape magnetic anisotropy specifically in the lower layer, providing a deterministic magnetization direction (parallel to track width) without requiring additional bias magnetic fields, thus maintaining detection precision while simplifying the overall structure.
Solution Approach 2:
The patent employs asymmetry by designing the lower magnetic layer with a larger area compared to the upper magnetic layer. This asymmetric area configuration creates shape magnetic anisotropy that naturally aligns the magnetization direction of the lower layer parallel to the track width direction, eliminating the need for complex bias field arrangements and improving manufacturing consistency.
2Measurement precision
If the magnetization directions of upper and lower magnetic layers are made anti-parallel to increase output change, then the detection sensitivity is improved, but the magnetization direction stability without bias field deteriorates
Solution Approach 1:
The patent changes the geometric parameter (area) of the magnetic layers, making the lower magnetic layer larger than the upper layer in the track width direction. This parameter change creates shape magnetic anisotropy that stabilizes the magnetization direction parallel to the track width, enabling consistent anti-parallel alignment between layers without requiring bias fields, thus maintaining both sensitivity and stability.
3Measurement precision
If the layer thickness is reduced to improve linear recording density, then the recording density is improved, but the magnetization direction control becomes more difficult and manufacturing precision deteriorates
Solution Approach 1:
The patent applies local quality by creating area asymmetry specifically in the lower magnetic layer, which generates shape magnetic anisotropy that naturally determines the magnetization direction parallel to the track width. This local structural feature provides robust magnetization control that is insensitive to small variations in layer thickness, enabling high recording density while maintaining manufacturing precision.
4Productivity
If multiple magnetic field detecting elements are produced to increase productivity, then the output quantity is improved, but the variability in magnetization directions increases and detection precision deteriorates
Solution Approach 1:
The patent employs asymmetry in the layer areas to create shape magnetic anisotropy that naturally aligns magnetization directions parallel to the track width. This asymmetric design provides a self-aligning mechanism that is insensitive to manufacturing variations, ensuring consistent magnetization directions across multiple elements produced in mass production, thus maintaining detection precision while increasing productivity.
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 configuration improves detection performance and productivity by maintaining consistent magnetization directions, reducing the effective read track width, and minimizing crosstalk effects in magnetic recording devices with narrow track widths.
Implementation Method 1
a non-magnetic intermediate layer sandwiched between the free layers... exchange coupling with the pinned layer
Implementation Method 2
a bias magnetic layer which is provided on a surface of said stack opposite to an air bearing surface, and wherein said bias magnetic layer applies a bias magnetic field to said upper magnetic layer and said lower magnetic layer in a direction perpendicular to the air bearing surface
Implementation Method 3
The CPP element has a stack including a magnetic layer (free layer) whose magnetization direction changes corresponding to an external magnetic field... electrical resistance of sense current that flows in a direction perpendicular to the film surface of the spin-valve film is changed
Implementation Method 4
insulating layers which are provided on both sides of said stack in a track width direction thereof, wherein a stepped portion is formed so that a length of said upper magnetic layer in the track width direction is different from that of said lower magnetic layer
Data Source
AI summary
A magnetic field detecting element comprises a stack including upper and lower magnetic layers, and a non-magnetic intermediate layer sandwiched therebetween, wherein magnetization of the magnetic layers changes in accordance with an external magnetic field; upper and lower shield electrode layers sandwiching the stack in a direction of stacking, wherein the upper and lower shield electrode layers supply sense current in the direction of stacking, and magnetically shield the stack; a bias magnetic layer provided on a surface of the stack opposite to an air bearing surface, and wherein the bias magnetic layer applies a bias magnetic field to the upper and lower magnetic layers in a direction perpendicular to the air bearing surface; and insulating layers provided on both sides of the stack in a track width direction thereof, wherein the stack has a stepped portion formed at the non-magnetic intermediate layer.