Magneto-resistive Element Spacer and Cover Layer Oxidation Control
Solution Overview
Problem
Conventional magneto-resistive effect (MR) elements face challenges in achieving high recording density due to difficulties in reducing the read gap and maintaining a large MR ratio, particularly when anti-ferromagnetic layers are not used, and existing spacer and cover layer configurations do not effectively prevent oxidation of magnetic layers.
Innovation Solution
The use of a spacer layer composed primarily of gallium oxide, zinc oxide, or magnesium oxide, combined with a cover layer of gallium oxide, which enhances the MR ratio by maintaining a wide band gap and preventing oxidation of adjacent magnetic layers, allowing for a larger MR ratio and improved recording density without the need for anti-ferromagnetic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the read gap is reduced to about 20 nm to achieve high recording density, then recording density is improved, but placing an anti-ferromagnetic layer within the read gap becomes difficult
Solution Approach 1:
The invention extracts and removes the anti-ferromagnetic layer from the conventional spin valve structure. By using a nonmagnetic metal layer instead, the structure achieves the necessary magnetic properties without requiring the anti-ferromagnetic layer, thus enabling read gap reduction to 20 nm while maintaining functionality.
Solution Approach 2:
The invention changes the material parameter of the spacer layer from conventional materials to specific oxide materials (In2O3, GaOx, ZnO, SnO2) with controlled thickness (0.3-2.0 nm). This parameter change enables achieving large MR ratio without anti-ferromagnetic layers, resolving the contradiction between read gap reduction and layer placement difficulty.
2Reliability
If conventional Al2O3 is used as the cover layer to maintain insulation, then insulation property is improved, but the MR ratio is reduced due to direct contact with magnetic layers
Solution Approach 1:
The invention introduces a nonmagnetic metal layer as an intermediary between the oxide spacer layer and the magnetic layers. This intermediary layer prevents direct contact between Al2O3 and magnetic layers, eliminating the harmful oxidation effect while maintaining the insulation function of the cover layer structure.
Solution Approach 2:
The invention creates a composite cover layer structure combining nonmagnetic metal layers with oxide layers. This composite structure simultaneously provides insulation properties and protects the magnetic layers from oxidation, resolving the contradiction between insulation and MR ratio maintenance.
3Length of stationary object
If a nonmagnetic metal layer is used instead of anti-ferromagnetic layer to reduce read gap, then read gap reduction is achieved, but the MR ratio becomes insufficient
Solution Approach 1:
The invention optimizes the thickness parameter of the nonmagnetic metal layer (0.3-2.0 nm) and selects specific materials (In2O3, GaOx, ZnO, SnO2) to achieve the right balance between maintaining a small read gap and ensuring sufficient MR ratio for 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 results in a higher MR ratio and improved recording density by preventing oxidation of magnetic layers and maintaining a wide band gap, even in an amorphous state, thus enhancing the performance of MR elements in hard disk drives.
Implementation Method 1
The spacer layer is provided with a main spacer layer that is composed of gallium oxide, zinc oxide or magnesium oxide as a primary component, wherein parts of side surfaces of the stack form parts of an air bearing surface; and a cover layer that covers at least another part of the side surfaces of the stack and that is composed of gallium oxide as a primary component
Implementation Method 2
a stack, being a pillar or trapezoidal stack, including first and second magnetic layers in which a relative angle formed by magnetization directions changes according to an external magnetic field
Data Source
AI summary
An MR element includes a stack, being a pillar or trapezoidal stack, including first and second magnetic layers in which a relative angle formed by magnetization directions changes according to an external magnetic field, and a spacer layer that is positioned between the first magnetic layer and the second magnetic layer, and that is provided with a main spacer layer that is composed of gallium oxide, zinc oxide or magnesium oxide as a primary component, wherein, one part of side surfaces of the stack forms a part of an air bearing surface; and a cover layer that covers at least another part of the side surfaces of the stack and that is composed of gallium oxide as a primary component.