Magnetoresistive Element Intermediate Layer Design
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Solution Overview
Problem
Current magnetoresistive elements face challenges in achieving high recording density and high signal-to-noise ratio due to limitations in reducing the areal resistance of the intermediate layer, leading to noise issues and difficulties in increasing current, while also struggling to narrow the gap between reproducing shields in magnetic recording devices.
Innovation Solution
A magnetoresistive element is designed with a structure that includes a first magnetic layer, a second magnetic layer, and an intermediate layer containing oxygen and at least one element of Cu, Au, and Ag, with a second layer of Mg and oxygen between the first and second magnetic layers, allowing for a low areal resistance and improved MR change rate through heat treatment and precise layer thickness control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the areal resistance of the intermediate layer is reduced to achieve high transfer rate and high S/N ratio, then the reproduction resistance can be maintained at 0.5 kΩ to 1 kΩ, but noise problems occur due to spin torque and it becomes difficult to increase current
Solution Approach 1:
The patent changes the material composition parameters of the intermediate layer by introducing a specific oxide layer containing Cu, Ag, or Au in combination with Zn, Al, or Mg. This compositional parameter change achieves an optimal balance between areal resistance (0.1-0.3 Ωμm²) and noise performance, resolving the contradiction between maintaining low resistance for high S/N ratio and avoiding spin torque noise.
Solution Approach 2:
The patent employs composite material structure in the intermediate layer by combining noble metal oxides (Cu, Ag, Au) with zinc oxide, aluminum oxide, or magnesium oxide. This composite approach creates a material system that simultaneously achieves low areal resistance and high noise immunity, eliminating the need for current-constricting structures and enabling stable operation at optimal resistance levels.
2Manufacturing precision
If a current-constricting structure with metal conducting path in insulating oxide layer is used to reduce areal resistance, then the areal resistance can be lowered, but when the reproducing element is made smaller, the number of conducting paths decreases resulting in wider variation in areal resistance
Solution Approach 1:
The patent changes from a current-constricting structure to a uniform conductive oxide layer structure. By adjusting the composition parameters (incorporating Cu, Ag, or Au with Zn, Al, or Mg oxides) and thickness parameters (5-20 nm range), the patent achieves consistent areal resistance (0.1-0.3 Ωμm²) across different element sizes, eliminating the variation problem associated with scaled-down current-constricting structures.
3Measurement precision
If the gap between reproducing shields is narrowed and TMR element thickness is reduced to improve resolution in linear recording density direction, then the resolution is improved, but the multi-layer structure of today's reproducing element makes it difficult to reduce the overall thickness
Solution Approach 1:
The patent changes the thickness parameter of the intermediate layer to an optimized range of 5-20 nm, which is thinner than conventional tunneling-conduction oxide layers. This parameter reduction in layer thickness contributes to overall TMR element thinning, enabling narrower gap between reproducing shields and improved linear recording density resolution while maintaining structural integrity.
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
The solution achieves a high MR change rate and low areal resistance, enabling high output and signal-to-noise ratio, and allows for the narrowing of the gap between reproducing shields, thereby enhancing recording density and device performance.
Implementation Method 1
A magnetoresistive element is designed with a structure that includes a first magnetic layer, a second magnetic layer, and an intermediate layer containing oxygen and at least one element of Cu, Au, and Ag, with a second layer of Mg and oxygen between the first and second magnetic layers
Data Source
AI summary
A magnetoresistive element according to an embodiment includes: a first magnetic layer, a second magnetic layer, and an intermediate layer disposed between the first magnetic layer and the second magnetic layer, the intermediate layer including: a first layer containing oxygen and at least one element of Cu, Au, and Ag; and a second layer containing Mg and oxygen, the second layer being disposed between the first layer and the second magnetic layer.