Magnetic Head Shielding with Exchange Anisotropy Bias
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Solution Overview
Problem
Existing thin film magnetic heads face challenges in applying sufficient bias to free layers while maintaining side shield functionality, particularly in high-density recording media, due to limitations in antiferromagnetic coupling layers and materials used.
Innovation Solution
A method of manufacturing a magnetic head with a multilayer film configuration that includes forming a soft magnetic layer on both sides of the MR element and applying an anisotropy layer to magnetize the soft magnetic layer in a predetermined direction, providing exchange anisotropy and improving the bias magnetic field strength and direction applied to the MR element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If soft magnetic layers are added on both sides of the MR element to suppress side reading, then side reading suppression is improved, but the ability to apply sufficient bias magnetic field to the free layer deteriorates
Solution Approach 1:
The patent segments the magnetic head structure into distinct functional regions: soft magnetic layers are placed only on the outer sides of the MR element to suppress side reading, while hard magnetic bias layers are positioned directly adjacent to the free layer to provide sufficient bias magnetic field. This spatial segmentation allows each layer type to perform its specialized function without interference.
Solution Approach 2:
The patent applies different magnetic material properties to different locations: soft magnetic materials with high permeability are used where flux absorption is needed (outer sides), while hard magnetic materials with high coercivity are used where strong localized bias fields are required (adjacent to free layer). This local optimization of material properties resolves the contradiction between side shielding and bias application.
2Device complexity
If antiferromagnetic coupling layers are used to provide self bias function, then device complexity is reduced, but manufacturing precision and performance improvement are limited due to material constraints
Solution Approach 1:
The patent changes the magnetic parameters of the bias layers by using hard magnetic materials with high coercivity values, enabling the generation of strong bias magnetic fields. By adjusting the thickness and magnetization strength of these hard magnetic layers, precise control over the bias field applied to the free layer is achieved, overcoming the limitations of antiferromagnetic coupling layers.
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 ensures sufficient bias is applied to the MR element, enhancing the bias magnetic field strength and direction, while maintaining effective side shielding, thus improving the performance of the thin film magnetic head in high-density recording applications.
Implementation Method 1
forming an anisotropy application layer on the second shield layer, the anisotropy application layer providing exchange anisotropy to the soft magnetic layer so as to magnetize the soft magnetic layer in a predetermined direction
Implementation Method 2
Since a soft magnetic material absorbs a magnetic flux from adjacent tracks, a noise effect due to the magnetic flux from the adjacent tracks is suppressed
Implementation Method 3
The bias magnetic layer applies a bias magnetic field to the free layer to change the free layer to a single magnetic domain
Implementation Method 4
an MR element configured with a multilayer film... an element provided with a spin valve film... The SV film is sandwiched by a pair of shields that are electrodes for supplying a sense current
Data Source
AI summary
A method of manufacturing a magnetic head, including a magneto resistance effect (MR) element that reads a magnetic recording medium, is disclosed. A multilayer film is formed on a shield layer. Unnecessary portions of the multilayer film are removed from both sides of the MR element in a first direction orthogonal to a lamination direction of the multilayer film and parallel to the MR element surface facing the magnetic recording medium. An insulating layer is formed on a surface exposed by removal of the unnecessary portions. An integrated soft magnetic layer covering both sides of the MR element in the first direction and an upper side of the MR element is formed, thereby configuring a second shield layer. An anisotropy application layer is formed on the second shield layer, thereby providing exchange anisotropy to the soft magnetic layer, and magnetizing the soft magnetic layer in a predetermined direction.