Magnetic Head Side Shields With Antiferromagnetic Layers
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Solution Overview
Problem
Magnetic heads used in magnetic storage devices have slow response times due to long relaxation times of the side shields, which affect the response speed and track density in magnetic recording and reproducing devices.
Innovation Solution
A magnetic head design featuring side shields with a stacked structure of magnetic and nonmagnetic layers, where the nonmagnetic layers include Ru, Cu, or Cr, and are antiferromagnetically coupled to reduce the formation of large magnetic domains and enhance magnetization stability, thereby reducing the relaxation times of the side shields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional side shield structure is used, then device complexity is low, but response speed is slow due to long relaxation times
Solution Approach 1:
The side shield is segmented into multiple magnetic layers and nonmagnetic layers stacked alternately. Each magnetic layer is separated by nonmagnetic spacer layers, dividing the continuous magnetic structure into discrete magnetic domains. This segmentation reduces the relaxation time by limiting the size of magnetic domains that need to flip during switching operations.
Solution Approach 2:
The side shield uses a composite structure combining magnetic materials (such as CoFe, NiFe) and nonmagnetic materials (such as Ru, Cu, Cr). The alternating layers of magnetic and nonmagnetic materials create a composite structure where the nonmagnetic layers act as spacers that prevent formation of large magnetic domains, thereby reducing relaxation times while maintaining shielding functionality.
2Speed
If side shield relaxation time is reduced, then response speed increases, but manufacturing precision requirements increase
Solution Approach 1:
The invention optimizes the thickness parameters of the nonmagnetic spacer layers and magnetic layers to achieve the desired relaxation time. By carefully selecting and controlling the thickness of each layer (e.g., nonmagnetic layer thickness between 0.3-2.2 nm), the design achieves reduced relaxation times while maintaining manufacturability through established thin-film deposition techniques.
3Stability of the object's composition
If alternating magnetic and nonmagnetic layers are used, then magnetization stability improves, but device complexity increases
Solution Approach 1:
The side shield magnetic structure is segmented into multiple discrete magnetic layers separated by nonmagnetic layers. This segmentation creates multiple independent magnetic domains that can be controlled individually, improving magnetization stability by preventing the formation of large, unstable magnetic domains while maintaining the overall shielding function.
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 results in a significant reduction of side shield relaxation times from 1.7 ns to 0.8 ns or less, enhancing the response speed and track density of magnetic recording and reproducing devices.
Implementation Method 1
the nonmagnetic layers include Ru, Cu, or Cr, and are antiferromagnetically coupled to reduce the formation of large magnetic domains and enhance magnetization stability
Data Source
AI summary
According to one embodiment, a magnetic head includes first and second shields, a magnetic pole, and a trailing shield. The magnetic pole is provided between the first and second shields. The trailing shield is separated from the magnetic pole. The first shield includes first magnetic layers and first nonmagnetic layers arranged alternately along a first stacking direction. The first nonmagnetic layers include at least one selected from the group consisting of Ru, Cu, and Cr. Thicknesses of the first nonmagnetic layers each is not less than 0.3 nanometers and not more than 2.2 nanometers. The second shield includes second magnetic layers and second nonmagnetic layers arranged alternately along a second stacking direction. The second nonmagnetic layers include at least one selected from the group consisting of Ru, Cu, and Cr. Thicknesses of the second nonmagnetic layers each is not less than 0.3 nanometers and not more than 2.2 nanometers.