Magneto-Resistive Reader Read Shields Reference Layer Magnetization
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Solution Overview
Problem
Existing magneto-resistive read heads face challenges in reducing the read gap length without compromising the amplitude and noise of the readout signal, limiting their down-track and cross-track resolution.
Innovation Solution
The use of read shields to maintain a reference layer magnetization, eliminating the need for a pinned reference layer and incorporating spacer layers and a Ruderman-Kittel-Kasuya-Yosida (RKKY) interlayer coupling to reduce the read gap length while maintaining signal quality, allowing for a thicker sense layer to minimize thermal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the read gap length is reduced to improve resolution, then down-track and cross-track resolution are enhanced, but the amplitude and noise of the readout signal are compromised
Solution Approach 1:
The patent introduces read shields as intermediary magnetic structures positioned adjacent to the sense layer. These shields act as mediators that generate magnetic fields to pin the magnetization of the reference layer, enabling the use of thinner spacer layers and reduced read gap lengths while maintaining signal quality. The shields serve as the intermediary element that resolves the contradiction between reduced gap length and signal amplitude.
Solution Approach 2:
The patent changes the magnetic field configuration parameters by introducing external magnetic fields through the read shields. This allows the reference layer magnetization to be pinned in a controlled manner, enabling the read gap to be reduced to 10 nanometers or less while maintaining adequate signal amplitude and reducing thermal noise through the thicker sense layer.
2Productivity
If the read gap length is reduced to improve resolution, then kilo flux change per inch and kilo track per inch are increased, but flux capture from neighboring tracks increases
Solution Approach 1:
The read shields serve as magnetic intermediaries that confine and direct the magnetic flux. By positioning the shields adjacent to the sense layer and using them to pin the reference layer magnetization, the shields create a controlled magnetic environment that enhances the flux from the target track while reducing flux capture from neighboring tracks, thereby improving KTPI without the harmful effect of increased crosstalk.
3Stability of the object's composition
If a pinned reference layer is used to maintain magnetization, then reference layer magnetization is stable, but the read gap length cannot be reduced
Solution Approach 1:
The patent replaces the conventional pinned reference layer structure with an alternative approach using read shields as intermediaries. The shields generate magnetic fields that pin the reference layer magnetization externally, eliminating the need for a thick pinned layer within the read gap. This allows the read gap to be reduced to 10 nanometers or less while maintaining magnetization stability.
Solution Approach 2:
The patent moves the magnetization pinning mechanism from the spatial dimension within the read gap to an external magnetic field dimension. By using read shields positioned adjacent to the sense layer and generating external magnetic fields, the system achieves magnetization pinning without occupying space within the read gap, thereby enabling reduced gap length.
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 approach reduces the read gap length to 10 nanometers or less, enhancing down-track and cross-track resolution by half, and increasing the kilo flux change per inch (KFCI) and kilo track per inch (KTPI) while maintaining signal linearity and reducing flux capture from neighboring tracks.
Implementation Method 1
The use of read shields to maintain a reference layer magnetization
Implementation Method 2
Various techniques can be implemented to implement a magneto-resistive reader, such as tunnel magneto-resistance (TMR) of magnetic tunnel junctions (MTJ)
Implementation Method 3
the coupling layer can produce a Ruderman-Kittel-Kasuya-Yosida (RKKY) interlayer coupling between the first shield and the first reference layer
Data Source
AI summary
The present embodiments relate to magneto-resistive read heads that can utilize read shields to maintain a reference layer magnetization. A magneto-resistive head can include a first shield and a second shield disposed adjacent to the first shield, with a distance between the shields forming a read gap. The magneto-resistive head can also include a first spacer layer disposed in the read gap. The magneto-resistive head can also include a first reference layer disposed in the read gap adjacent to the first spacer layer. A first reference layer magnetization direction can be set based at least by a first shield magnetization direction. The magneto-resistive head can also include a sense layer disposed in the read gap between the first spacer layer and the second shield.