Shield Layer Width Tapering for Magnetic Head Track Erase
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Solution Overview
Problem
Thin-film magnetic heads for perpendicular magnetic recording systems face issues with track erase and output variations due to the magnetization of bias field applying layers, as well as wide-range adjacent track erase, which affect recording density and reliability.
Innovation Solution
The design incorporates read and write shield layers with specific width changing portions and plane geometries that decrease in width continuously, featuring a circumscribed rectangle geometry with cut-off corners and line-symmetric or nearly line-symmetric portions, to suppress track erase and output variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If read shield layers and write shield layers are used to prevent magnetic field interference, then magnetic field shielding capability is improved, but track erase and output variations occur due to magnetization of bias field applying layers
Solution Approach 1:
The patent applies different geometric configurations to different regions of the shield layers. Specifically, the read shield layer has a first region with a first geometric configuration and a second region with a second geometric configuration, while the write shield layer has a first region with a first geometric configuration and a second region with a second geometric configuration. This local differentiation allows optimization of magnetic field shielding in different areas while controlling unwanted magnetization effects.
Solution Approach 2:
The patent employs asymmetric geometric configurations for the shield layers. The first geometric configuration differs from the second geometric configuration in terms of shape, orientation, or dimensions. This asymmetry is designed to control the magnetization behavior of bias field applying layers and reduce track erase and output variations while maintaining effective magnetic field shielding.
2Object-affected harmful factors
If shield layers with larger area are used to enhance shielding effect, then magnetic field shielding capability is improved, but wide-range adjacent track erase occurs
Solution Approach 1:
The patent divides the shield layers into multiple regions with different geometric configurations. The first region has a first geometric configuration optimized for shielding, while the second region has a second geometric configuration that limits the spread of magnetic fields to adjacent tracks. This local differentiation resolves the contradiction between providing adequate shielding area and preventing wide-range adjacent track erase.
Solution Approach 2:
The shield layers are segmented into distinct regions with different geometric characteristics. This segmentation allows the overall shield structure to provide comprehensive magnetic field shielding while specific segments control the magnetic field distribution to prevent interference with adjacent tracks.
3Measurement precision
If bias field applying layers are magnetized to apply bias magnetic field to free layer, then read head sensitivity is improved, but output variations occur due to magnetization instability
Solution Approach 1:
The patent applies different geometric configurations to different regions of the shield layers that interact with bias field applying layers. This local geometric differentiation stabilizes the magnetization of bias field applying layers in critical regions while maintaining the bias field application function, thereby reducing output variations and improving read head sensitivity.
Solution Approach 2:
The asymmetric geometric configurations of the shield layers create stable magnetic field distributions that prevent unwanted magnetization changes in bias field applying layers. This asymmetry is specifically designed to maintain consistent magnetization states, reducing output variations while preserving read head sensitivity.
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 design effectively reduces the occurrence of track erase, output variations, and wide-range adjacent track erase, enhancing the reliability and recording density of thin-film magnetic heads by stabilizing the magnetic state of the shield layers.
Implementation Method 1
a magnetoresistive element reading data stored on the recording medium by means of a perpendicular magnetic recording system
Implementation Method 2
bias field applying layers for applying a bias magnetic field to the magnetoresistive element
Implementation Method 3
an antiferromagnetic layer disposed adjacent to one of the surfaces of the pinned layer farther from the nonmagnetic conductive layer. The free layer is a layer in which the direction of magnetization changes in response to a signal magnetic field. The pinned layer is a ferromagnetic layer in which the direction of magnetization is fixed.
Implementation Method 4
The read head further comprises a pair of read shield layers disposed to sandwich the GMR element. The read shield layers are provided for preventing the GMR element from being influenced by a magnetic field from bits that are not opposed thereto.
Implementation Method 5
a pole layer having an end face located in the medium facing surface, allowing a magnetic flux corresponding to the field generated by the coil to pass therethrough, and generating a write magnetic field for writing the data on the recording medium
Data Source
AI summary
A thin-film magnetic head comprises: a magnetoresistive element: first and second read shield layers disposed to sandwich the magnetoresistive element; and bias field applying layers for applying a bias magnetic field to the magnetoresistive element. Each of the first and second read shield layers has: a first end face located in a medium facing surface; a second end face opposite to the first end face; a first width changing portion that continuously decreases in width as the distance from the first end face decreases; and a second width changing portion that continuously decreases in width as the distance from the second end face decreases.