Spin Tunneling Element With Composite Free Layer
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Solution Overview
Problem
Conventional spin tunneling elements used in magnetic recording technology face challenges with high magnetostriction and interlayer exchange coupling, leading to instability and reduced signal quality, particularly when using CoFeB as the free layer, which compromises their suitability for read heads.
Innovation Solution
A spin tunneling element is designed with a crystalline barrier layer and a free layer comprising two ferromagnetic layers with different crystal structures and textures, where the first ferromagnetic layer is BCC with a [100] texture and the second is FCC, utilizing CoFeB and NiFe to achieve low magnetostriction and interlayer exchange coupling, while maintaining high magnetoresistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CoFeB is used as the free layer to achieve high magnetoresistance, then the magnetoresistance signal is improved, but the magnetostriction and interlayer exchange coupling increase leading to instability
Solution Approach 1:
The free layer is constructed as a composite structure combining CoFeB (providing high magnetoresistance) with NiFe (providing low magnetostriction and soft magnetic properties). This composite approach allows the system to simultaneously achieve high signal strength and stability by leveraging the complementary properties of the two materials.
2Device complexity
If a single ferromagnetic layer is used to simplify the structure, then the device complexity is reduced, but the soft magnetic performance and stability are compromised
Solution Approach 1:
The free layer is segmented into two distinct ferromagnetic layers with different crystal structures and magnetic properties. The first layer (CoFeB) provides high magnetoresistance while the second layer (NiFe) provides soft magnetic characteristics. This segmentation allows each layer to optimize its function independently, achieving both simplicity in concept and performance in practice.
3Loss of energy
If the barrier layer is made crystalline to achieve low resistance, then the electrical resistance is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The barrier layer is designed with specific crystallographic parameters - a body-centered cubic (BCC) structure with a dominant [100] orientation. By controlling these crystallographic parameters during fabrication, the layer achieves low electrical resistance through optimized electron transport pathways while the parameter specifications provide clear manufacturing targets for quality control.
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 provides a spin tunneling element with improved soft magnetic properties and high magnetoresistance, ensuring stability and signal quality suitable for use in read heads without significantly reducing the signal strength.
Implementation Method 1
conventional spin tunneling element 10 includes a conventional pinned layer 16 having a magnetization 17, a conventional barrier layer 18, a conventional free layer 20 having a magnetization 21
Implementation Method 2
The magnetization 17 of the conventional pinned layer 16 is fixed, or pinned, in a particular direction, typically by an exchange-bias interaction with the AFM layer 14
Implementation Method 3
a low magnetostriction of λs being not more than 1.0×10−6 (or not less than −1.0×10−6) is desired
Data Source
AI summary
The method and system for providing a spin tunneling element are disclosed. The method and system include depositing a pinned layer, a barrier layer, and a free layer. The barrier layer has a first crystal structure and a texture. The free layer includes a first ferromagnetic layer and a second ferromagnetic layer. The first ferromagnetic is adjacent to the second ferromagnetic layer and between the second ferromagnetic layer and the barrier layer. The first ferromagnetic layer has the first crystal structure and the texture, while the second ferromagnetic layer has a second crystal structure different from the first crystal structure.