Magnetic Detecting Element Free Layer Torque Offset
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Solution Overview
Problem
Magnetic detecting elements with pinned magnetic layers face issues of output asymmetry and pin inversion, leading to deterioration in symmetry and reproduced output, especially when external forces are applied.
Innovation Solution
A magnetic detecting element with a multi-layer film structure where the pinned magnetic layer's magnetization direction is pinned in the uniaxial direction, and a free magnetic layer is layered with a nonmagnetic material layer, with the second free magnetic layer having a greater magnetic film thickness than the first free magnetic layer to offset torque and maintain orthogonal magnetization directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the magnetic film thickness of the second free magnetic layer is increased to offset torque and maintain orthogonal magnetization directions, then output symmetry is improved, but device complexity increases
Solution Approach 1:
The free magnetic layer is divided into two separate layers (first free magnetic layer and second free magnetic layer) with different thicknesses. This segmentation allows independent optimization of each layer's contribution to torque offset and magnetization direction control, achieving output symmetry while maintaining manageable structural complexity through modular design
Solution Approach 2:
Different regions of the free magnetic layer are given different properties by varying the thickness of the second free magnetic layer relative to the first. This local quality differentiation enables precise control over torque distribution and magnetization orientation in specific areas, improving output symmetry without requiring uniform thickening of the entire free magnetic layer
2Manufacturing precision
If the magnetization direction of the free magnetic layer is maintained orthogonal to the pinned magnetic layer, then output symmetry is maintained during pin inversion, but the device becomes more sensitive to external magnetic fields
Solution Approach 1:
The torque offset mechanism using the second free magnetic layer acts as a counterweight to external magnetic field disturbances. By carefully balancing the magnetic moments and thicknesses of the two free magnetic layers, the system creates an internal torque that compensates for external field effects, maintaining orthogonal magnetization directions and output symmetry while reducing sensitivity to harmful external magnetic fields
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 configuration effectively suppresses changes in magnetization direction and maintains output symmetry and reproduced output even during pin inversion, with output asymmetry and standardized output changes minimized to 20% or less.
Implementation Method 1
the magnetic film thickness of the second free magnetic layer in contact with the nonmagnetic material layer is greater than the magnetic film thickness of the first free magnetic layer to offset torque and maintain orthogonal magnetization directions
Implementation Method 2
a pinned magnetic layer of which the magnetization direction is pinned in the uniaxial direction
Implementation Method 3
a sensing current flowing in a parallel direction of film surfaces of the pinned magnetic layer, the nonmagnetic material layer, and the free magnetic layer via the first electrode layer and the second electrode layer
Data Source
AI summary
A magnetic detecting element, which can suppress change in output asymmetry even if the magnetization direction of a pinned magnetic layer is changed 180°, is provided. The magnetic-film-thickness of a second free magnetic layer is increased so as to be greater than that of a first free magnetic layer and offset the torque applied to the second free magnetic layer with that applied to the first free magnetic layer when the sensing current magnetic field occurs. Thus, change in the magnetization direction of the free magnetic layer before and after a sensing current is applied in the magnetic detecting element can be suppressed. The orthogonal state between the free magnetic layer and the pinned magnetic layer is maintained even when a sensing current in the same direction as that before the occurrence is applied in the magnetic detecting element wherein pin inversion occurred, and the output asymmetry is maintained suitably.