CPP GMR Sensor with Inclined Shield Magnetization for Narrow Read Gap
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Solution Overview
Problem
Current magneto-resistive effect devices face challenges in achieving ultra-high recording density due to limitations in narrowing the read gap and maintaining a stable bias magnetic field, especially with the 'scissors type GMR device' which requires a thick permanent magnet to generate sufficient bias, compromising the device's narrow read gap advantage.
Innovation Solution
A CPP (current perpendicular to plane) structure with a magneto-resistive effect unit sandwiched between upper and lower shield layers, where the first and second ferromagnetic layers are exchange coupled via a nonmagnetic metal intermediate layer, and at least one shield layer has an inclined magnetization structure to apply a bias magnetic field, allowing for a narrowed read gap and stable magneto-resistive effect change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a thick permanent magnet is used to generate sufficient bias magnetic field, then the bias magnetic field strength is improved, but the read gap width increases
Solution Approach 1:
The invention extracts the bias magnetic field generation function from the permanent magnet and relocates it to the shield layers. The shield layers are designed with inclined magnetization structures that generate the necessary bias magnetic field, eliminating the need for a thick permanent magnet and thereby maintaining a narrow read gap.
Solution Approach 2:
The shield layers perform dual functions: they provide magnetic shielding and simultaneously generate the bias magnetic field through their inclined magnetization structures. This multi-functionality eliminates the need for a separate permanent magnet component.
2Productivity
If the read gap is narrowed to achieve ultra-high recording density, then the recording density is improved, but the bias magnetic field strength decreases
Solution Approach 1:
The invention extracts the bias magnetic field generation function from the permanent magnet and relocates it to the shield layers. The shield layers are designed with inclined magnetization structures that generate the necessary bias magnetic field, eliminating the need for a thick permanent magnet and thereby maintaining a narrow read gap.
Solution Approach 2:
The invention changes the magnetization direction parameter of the shield layers from parallel to inclined relative to the track width direction. This parameter change enables the shield layers to generate a longitudinal bias magnetic field that is effective for ultra-high density recording while maintaining a narrow read gap.
3Length of moving object
If the device area is reduced to accommodate narrower tracks, then the track width is improved, but the heat dissipation efficiency deteriorates
Solution Approach 1:
The CPP-GMR device structure allows the device to self-manage heat dissipation through its vertical current path and multilayer configuration, which provides efficient thermal conduction paths without requiring increased device area.
4Productivity
If the shield gap is reduced to increase recording density, then the recording density is improved, but the device complexity increases
Solution Approach 1:
The shield layers perform dual functions: they provide magnetic shielding and simultaneously generate the bias magnetic field through their inclined magnetization structures. This multi-functionality eliminates the need for a separate permanent magnet component and simplifies the overall device structure while enabling ultra-high density recording.
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 enables a stable bias magnetic field application and improved reliability for ultra-high recording density, maintaining the narrow read gap advantage while ensuring sufficient resistance change, thus enhancing the performance of thin-film magnetic heads and magnetic disk systems.
Implementation Method 1
said first ferromagnetic layer and said second ferromagnetic layer are exchange coupled via said nonmagnetic metal intermediate layer such that where there is no bias magnetic field applied, their magnetizations are anti-parallel with each other
Implementation Method 2
at least one of said upper shield layer and said lower shield layer has an inclined magnetization structure with its magnetization inclining with respect to a track width direction, so that by magnetization of that inclined magnetization structure, a bias magnetic field can be applied to said first ferromagnetic layer and said second ferromagnetic layer
Implementation Method 3
a magneto-resistive effect device adapted to read the magnetic field intensity of magnetic recording media or the like as signals
Data Source
AI summary
The invention provides a magneto-resistive effect device of the CPP (current perpendicular to plane) structure, comprising a magneto-resistive effect unit, and an upper shield layer and a lower shield layer located with that magneto-resistive effect unit sandwiched between them, with a sense current applied in a stacking direction, wherein the magneto-resistive effect unit comprises a nonmagnetic metal intermediate layer, and a first ferromagnetic layer and a second ferromagnetic layer stacked and formed with that nonmagnetic metal intermediate layer sandwiched between them, wherein the first ferromagnetic layer and said second ferromagnetic layer are exchange coupled via the nonmagnetic metal intermediate layer such that where there is no bias magnetic field applied as yet, their magnetizations are anti-parallel with each other, and at least one of the upper shield layer and the lower shield layer has an inclined magnetization structure with its magnetization inclining with respect to a track width direction, so that by the magnetization of that inclined magnetization structure, a bias magnetic field can be applied to the first ferromagnetic layer and the second ferromagnetic layer. It is thus possible to obtain a magneto-resistive effect device of improved reliability that enables a structure capable of having a narrowed read gap (the gap between the upper shield and the lower shield) to be adopted to meet the recently demanded ultra-high recording density, allows a stable bias magnetic field to be applied in simple structure, and obtain a stable magneto-resistive effect change.