Amorphous Magnetic Underlying Layer for Narrow Gap Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing magnetic sensing elements struggle to decrease half-amplitude pulse width (PW50) while maintaining signal-to-noise ratio (SN ratio) and rate of change in resistance (Δ R/R) to increase recording density, as the underlying layer, typically composed of nonmagnetic materials like Ta, limits the narrowing of the gap between shield layers without deteriorating reproducing characteristics.
Innovation Solution
A magnetic sensing element with a multilayered film structure where the underlying layer is composed of an amorphous magnetic material, such as Co—X or Ni—Fe—Y, allowing for a narrower gap without affecting the crystalline orientation of other layers, and an insulating barrier layer like Al—O or Mg—O is used to maintain SN ratio and Δ R/R, enabling improved PW50 and recording density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the gap length between upper and lower shield layers is decreased to reduce PW50, then recording density can be increased, but reproducing characteristics such as rate of change in resistance (ΔR/R) deteriorate
Solution Approach 1:
The underlying layer material is changed from nonmagnetic (Ta) to amorphous magnetic material (Co—Fe—B), which fundamentally alters the magnetic field distribution and allows gap reduction without signal degradation. This parameter change in material composition enables simultaneous improvement in PW50 and maintenance of ΔR/R characteristics.
Solution Approach 2:
The patent employs a composite multilayered structure combining amorphous magnetic material (Co—Fe—B) with conventional materials (Ta, Co—Fe, Co—Cr—Pt) in specific configurations. The amorphous magnetic underlying layer works in conjunction with the shield layers and multilayered film to achieve optimized magnetic field control while maintaining signal integrity.
2Length of moving object
If the film thickness of the multilayered film is reduced to narrow the gap, then PW50 decreases, but individual layers already have minimum thickness of a few tens of A making further reduction difficult
Solution Approach 1:
The patent changes the material parameter of the underlying layer from nonmagnetic to amorphous magnetic material, which allows the gap length to be reduced without requiring further thinning of the multilayered film. The amorphous magnetic material's unique properties enable effective magnetic field control at smaller gap dimensions while maintaining layer thicknesses above the manufacturing minimum.
3Ease of manufacture
If Ta is used as the underlying layer to maintain simplicity, then manufacturing is easy, but PW50 cannot be effectively decreased without deteriorating SN ratio and ΔR/R
Solution Approach 1:
The underlying layer material is changed from Ta (nonmagnetic) to Co—Fe—B (amorphous magnetic), which fundamentally changes the magnetic field distribution characteristics. This parameter change enables effective PW50 reduction and SN ratio improvement while maintaining deposition process compatibility through sputtering methodology.
Solution Approach 2:
The patent discards the conventional Ta underlying layer approach and recovers performance through the amorphous magnetic material. The Ta layer is replaced entirely with Co—Fe—B, which provides the necessary magnetic properties that Ta cannot deliver, thereby recovering and improving PW50 and SN ratio characteristics.
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 use of an amorphous magnetic underlying layer and insulating barrier layer effectively decreases PW50 and improves SN ratio without compromising Δ R/R, thus enhancing recording density in magnetic sensing elements.
Implementation Method 1
tunneling magnetoresistive elements have such a structure that a multilayered film, which makes use of a tunneling magnetoresistance effect, is interposed between lower and upper shied layers
Data Source
AI summary
An underlying layer is composed of Co—Fe—B that is an amorphous magnetic material. Thus, the upper surface of the underlying layer can be taken as a lower shield layer-side reference position for obtaining a gap length (GL) between upper and lower shields, resulting in a narrower gap than before. In addition, since the underlying layer has an amorphous structure, the underlying layer does not adversely affect the crystalline orientation of individual layers to be formed thereon, and the surface of the underlying layer has good planarizability. Accordingly, PW50 (half-amplitude pulse width) and SN ratio can be improved more than before without causing a decrease in rate of change in resistance (Δ R/R) or the like, thereby achieving a structure suitable for increasing recording density.