CPP Magnetoresistive Element with Perpendicular Side Shields
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Solution Overview
Problem
Conventional MR elements in CPP structure face challenges in achieving high recording density due to limitations in narrowing the read gap length and maintaining proper magnetization direction regulation, especially when exposed to magnetic fields from adjacent tracks, which affects their operational reliability.
Innovation Solution
The MR element incorporates a CPP structure with a nonmagnetic layer sandwiched by ferromagnetic layers and an orthogonalizing bias function, accompanied by side shield layers with perpendicular magnetization, which are made of Co, Ni, and Fe, to maintain the magnetization direction regulation and enhance recording density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the read gap length is narrowed to increase recording density, then the recording density is improved, but the magnetization direction regulation becomes unstable due to magnetic field interference from adjacent tracks
Solution Approach 1:
The shield layer is segmented into a main shield layer and side shield layers. The side shield layers are positioned at both sides of the MR element in the track width direction and magnetized in the perpendicular direction, creating separate magnetic shielding zones that confine the magnetic field and prevent interference from adjacent tracks, thus maintaining magnetization direction stability even with narrow read gap length
Solution Approach 2:
The side shield layers act as intermediary magnetic shielding elements between the MR element and adjacent tracks. These perpendicular magnetized layers intercept and redirect magnetic field lines from adjacent tracks, preventing them from reaching the free layer and disrupting its magnetization direction, thereby protecting the magnetization regulation while enabling narrow read gap design
2Manufacturing precision
If the element area is reduced to achieve narrower track and higher density, then the recording density is improved, but the heat dissipating efficiency decreases leading to reliability issues
Solution Approach 1:
The side shield layers are strategically positioned only at the side regions of the MR element where magnetic field interference from adjacent tracks occurs. This localized shielding structure provides magnetic field confinement exactly where needed without adding unnecessary material or complexity to the central sensing region, optimizing the balance between magnetic field management and thermal performance
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 allows for further high-density recording in the track width direction while maintaining the initial magnetization state, improving the MR element's ability to detect external magnetic fields effectively and enhancing its operational stability.
Implementation Method 1
a magnetoresistive effect part (MR part) configured with a nonmagnetic layer, a first ferromagnetic layer that functions as first free layer and a second ferromagnetic layer that functions as a second free layer
Implementation Method 2
an orthogonalizing bias function part, which generates a bias magnetic field to regulate the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer, is formed on the rear side of the magnetoresistive effect part
Implementation Method 3
side shield layers are disposed on both sides in the width direction of the magnetoresistive effect part, the side shield layers are perpendicular magnetized layers with a magnetic shield function
Data Source
AI summary
An MR element in a CPP structure includes an MR part configured with a nonmagnetic layer, a first ferromagnetic layer that functions as first free layer and a second ferromagnetic layer that functions as a second free layer, and first and second ferromagnetic layers are laminated to sandwich the nonmagnetic intermediate layer, and a sense current flows in a lamination direction of the MR part, an orthogonalizing bias function part, which influences a substantial orthogonalization function for magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer, is formed on the rear side the MR part, side shield layers are disposed on both sides in the width direction of the MR part, the side shield layers are perpendicular magnetized layers with a magnetic shield function, and magnetization directions of the perpendicular magnetized layers are in an orthogonal direction that corresponds to the thickness direction.