Magneto-resistive Spacer Layer with Non-uniform Thickness
Solution Overview
Problem
Existing magneto-resistive (MR) elements face challenges in achieving a high MR ratio and reducing the read gap while maintaining a small track direction width of the spacer layer, as conventional methods struggle to control oxidation and nitriding processes effectively, leading to reduced MR ratios and manufacturing difficulties.
Innovation Solution
The MR element features a spacer layer with a film thickness that is larger at the side edge parts than at the central part in the track width direction, allowing current to flow through thinner sections, thereby increasing current density and achieving a large MR ratio without the need for anti-ferromagnetic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the track direction width of the spacer layer is reduced to increase recording density, then the read gap can be reduced, but it becomes difficult to control oxidation and nitriding processes, leading to reduced MR ratio
Solution Approach 1:
The spacer layer is designed with non-uniform thickness, having a first thickness in a first region and a second thickness in a second region. This local variation in thickness allows different regions to have different properties, enabling the central region to maintain appropriate thickness for manufacturing control while edge regions can be thinner to reduce overall track direction width and read gap.
2Productivity
If the track direction width of the spacer layer is reduced to increase recording density, then higher recording density is achieved, but the MR ratio is reduced due to oxidation of magnetic layers
Solution Approach 1:
By creating regions with different thicknesses in the spacer layer, the invention allows the central region to maintain sufficient thickness to prevent oxidation of magnetic layers, preserving MR ratio, while edge regions can be thinner to achieve the required small track direction width for high recording density.
Solution Approach 2:
The spacer layer is divided into multiple regions (first region and second region) with different thicknesses. This segmentation allows independent optimization of different areas: the central region for magnetic layer protection and the edge regions for size reduction, thereby simultaneously achieving high recording density and maintained MR ratio.
3Reliability
If conventional oxidation or nitriding is applied to narrow the spacer layer cross section, then the MR ratio can be increased, but the oxidation of magnetic layers reduces the MR ratio when track direction width is small
Solution Approach 1:
The non-uniform thickness design allows oxidation or nitriding processes to be applied selectively to edge regions without significantly affecting the central region where magnetic layers are located. This prevents harmful oxidation of magnetic layers while still achieving the desired cross-section narrowing for increased MR ratio.
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 effectively enhances the MR ratio and facilitates the reduction of the read gap, enabling higher recording densities while maintaining manufacturing feasibility, even at small track direction widths.
Implementation Method 1
a magneto-resistive effect (MR) element includes first and second magnetic layers in which a relative angle formed by magnetization directions changes in response to an external magnetic field, and a spacer layer positioned between the first magnetic layer and the second magnetic layer
Data Source
AI summary
A magneto-resistive effect (MR) element includes first and second magnetic layers in which a relative angle formed by magnetization directions changes in response to an external magnetic field, and a spacer layer positioned between the first magnetic layer and the second magnetic layer. The spacer layer, on an air bearing surface, has a larger film thickness at both side edge parts in a track width direction than a film thickness at a central part in a track width direction. When a region of the spacer layer on the air bearing surface is divided into quarters which are both side edge part regions and two central regions such that track width direction lengths are equivalent, an average film thickness of a region where the both side edge regions are combined is preferably larger than a region where the two central regions are combined.