Magneto-resistive Element Without Spacer Layer
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Solution Overview
Problem
Conventional magneto-resistive elements using spin-valve films face limitations due to the presence of a spacer layer, which can lead to spin-flip phenomena and reduced resistance variation, affecting their performance in sensing magnetism effectively.
Innovation Solution
A magneto-resistive element is designed without a spacer layer, utilizing a three-layer structure with a pinned layer, an external magnetic field sensing layer, and another pinned layer, where the external magnetic field sensing layer is directly adjacent to the pinned layers, allowing for a larger resistance variation and improved magnetoresistance ratio without the need for a spacer layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spacer layer is introduced in spin-valve film structure, then magnetic separation between pinned layer and free layer is achieved, but spin-flip phenomena occur and resistance variation is reduced
Solution Approach 1:
The invention removes the spacer layer from the spin-valve film structure entirely. By extracting this problematic intermediate layer, the patent eliminates the spin-flip phenomena that occurred at the spacer layer interfaces while maintaining magnetic separation through direct exchange coupling between the pinned layer and free layer in a magnetoresistive element with structure: substrate/pinned layer/free layer/tunnel barrier layer/pinned layer/antiferromagnetic layer. This extraction resolves the contradiction by eliminating the source of spin-flip effects that reduced resistance variation.
Solution Approach 2:
The patent employs a composite multilayer structure combining ferromagnetic layers (pinned layer and free layer) with a tunnel barrier layer (such as MgO). This composite structure enables direct magnetic interaction between ferromagnetic layers through the tunnel barrier, achieving both magnetic separation and high resistance variation without requiring a spacer layer. The combination of different material properties (ferromagnetism, tunneling barrier) creates a system that simultaneously achieves reliable magnetic separation and high measurement precision.
2Reliability
If a spacer layer is used in magneto-resistive element, then magnetic coupling between layers is reduced, but device complexity and film thickness increase
Solution Approach 1:
The invention extracts and removes the spacer layer from the magneto-resistive element structure, reducing the total number of layers and film thickness. The magnetic coupling control previously achieved through spacer layer thickness adjustment is replaced by direct exchange coupling between adjacent ferromagnetic layers, simplified by the tunnel barrier layer. This extraction reduces device complexity while maintaining reliable magnetic coupling control through the streamlined structure.
Solution Approach 2:
The patent merges the functions of magnetic separation and magnetic coupling control into a simpler structure where the tunnel barrier layer simultaneously provides electrical isolation and enables spin-dependent tunneling. By combining these functions and removing the spacer layer, the invention reduces film structure complexity while maintaining reliable magnetic coupling control through direct interaction between the pinned layer and free layer.
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 enhances the magneto-resistive effect, enabling a higher magneto-resistance ratio and improved sensitivity in magnetism sensing, while reducing the complexity and thickness of the film structure, making it suitable for high-density magnetic recording applications.
Implementation Method 1
a magneto-resistive film 10 which has a pinned layer 14, an external magnetic field sensing layer 15, and a pinned layer 16 stacked in this order, and exhibits a giant magneto-resistive effect
Implementation Method 2
the pinned layer 16 and the external magnetic field sensing layer 15 are directly close to each other, so that the magnetization directions of the pinned layer 16 and the external magnetic field sensing layer 15 are fixed by magnetic interaction
Data Source
AI summary
A magneto-resistive element includes: a first magnetic layer having a substantially fixed magnetization direction; a thin film layer disposed on the first magnetic layer and having at least one of oxide, nitride, oxynitride, and metal; and a second magnetic layer disposed on the thin film layer and having a substantially fixed magnetization direction.