Magneto-resistive Element Cap Layer Canceling Spin Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current magneto-resistive elements, particularly CPP-GMR elements, face challenges with magnetic noise due to the spin injection effect, which complicates achieving high sensitivity and narrow track widths in hard disk drives.
Innovation Solution
A magneto-resistive element structure is developed with a first electrode layer made of ferromagnetic materials like gold, silver, or ruthenium, which cancels the spin injection effect by allowing spin-polarized electrons to pass through, reducing magnetic influence on the free layer, and enabling a thinner film structure suitable for narrow shield gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large amount of electric current is applied to operate a CPP-GMR element, then the operating capability is improved, but magnetic noise due to spin injection effect occurs
Solution Approach 1:
The patent introduces a first electrode layer made of ferromagnetic material with specific magnetization direction to generate spin-polarized electrons that produce a magnetic field opposing the spin injection effect. This converts the harmful spin injection effect into a beneficial canceling effect, reducing magnetic noise while maintaining high operating current capability
Solution Approach 2:
The patent changes the magnetization direction parameter of the first electrode layer to be opposite to that of the pinned layer, creating a compensating magnetic field that counteracts the spin injection effect and reduces magnetic noise during high-current operation
2Length of moving object
If the film thickness is reduced to achieve narrower shield gaps, then the track width is narrowed, but the spin injection effect becomes more significant
Solution Approach 1:
The first electrode layer acts as an intermediary element between the pinned layer and the free layer. It generates a compensating magnetic field that mediates the interaction, reducing the spin injection effect's impact on the free layer while allowing the thin film structure to maintain narrow shield gaps
3Object-generated harmful factors
If a dual spin valve structure is used to cancel spin injection effect, then magnetic noise is reduced, but the film thickness increases
Solution Approach 1:
The patent extracts the spin injection effect cancellation function from the dual spin valve structure and implements it through a simpler first electrode layer configuration. This removes the need for additional pinned layers while maintaining noise reduction capability, thereby reducing overall film thickness
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 mitigates magnetic noise and allows for a smaller film thickness and narrower shield gaps, enhancing the sensitivity and performance of magneto-resistive elements in hard disk drives.
Implementation Method 1
only electrons having a spin direction that is directed in the same direction as the magnetization direction of the first electrode layer (spin polarized electrons) are allowed to pass through the first electrode layer
Implementation Method 2
A magneto-resistive element is arranged inside insulating films (inter-shield insulating films) which are provided between first and second shield layers
Data Source
AI summary
A magneto-resistive element has: a first stacked film assembly having a pinned layer, a spacer layer, and a free layer; a first electrode layer which is arranged such that the first layer is in contact with the first electrode layer on the other side of the first layer, the first electrode layer being made of a ferromagnetic material; and a second electrode layer which is arranged on a side that is opposite to the first electrode layer with regard to the first stacked film assembly. The first and second electrode layers are adapted to apply a sense current to the first stacked film assembly and the first layer in a direction that is perpendicular to layer surfaces. The first layer is made of gold, silver, copper, ruthenium, rhodium, iridium, chromium or platinum, or an alloy thereof.