CPP Magnetic Detecting Element with Magnetostriction-Enhancing Layers
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Solution Overview
Problem
Current CPP magnetic detecting elements face challenges in enhancing the GMR effect due to spin-independent scattering caused by Joule heat from antiferromagnetic layers and difficulty in fixing the magnetization of the pinned magnetic layer, which limits their ability to achieve high track density recording.
Innovation Solution
A CPP magnetic detecting element with a multilayer structure that includes a free magnetic layer, a nonmagnetic material layer, and a pinned magnetic layer, where the magnetization is fixed by uniaxial anisotropy and enhanced using magnetostriction-enhancing layers to increase the magnetoelastic energy, eliminating the need for antiferromagnetic layers and reducing spin-independent scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antiferromagnetic layers are used to fix the magnetization of the pinned magnetic layer, then the magnetization is fixed, but Joule heat is generated causing spin-independent scattering that reduces the GMR effect
Solution Approach 1:
The invention extracts and removes the antiferromagnetic layer from the magnetic detecting element structure. By eliminating this layer, the source of Joule heat generation is removed, thereby reducing spin-independent scattering and enhancing the GMR effect while maintaining magnetization fixation through alternative means
Solution Approach 2:
The invention introduces a nonmagnetic interlayer as an intermediary between the pinned magnetic layer and the free magnetic layer. This nonmagnetic interlayer serves as a mediator that allows magnetization fixation without requiring the antiferromagnetic layer, thus preventing Joule heat generation while maintaining the necessary magnetic properties
2Device complexity
If the magnetization of the pinned magnetic layer is not firmly fixed, then the structure is simpler, but distortion and asymmetry in reproduction waveforms increase
Solution Approach 1:
The invention changes the magnetic anisotropy parameter of the pinned magnetic layer by introducing uniaxial anisotropy. This parameter change firmly fixes the magnetization direction, reducing distortion and asymmetry in reproduction waveforms while maintaining a relatively simple overall structure
3Power
If the spin-dependent bulk scattering coefficient is increased to enhance the GMR effect, then the reproduction power increases, but the manufacturing precision requirements increase
Solution Approach 1:
The invention changes material parameters by selecting specific magnetic layer materials with appropriate spin-dependent bulk scattering coefficients. By carefully selecting materials and controlling their thicknesses, the reproduction power is enhanced while keeping manufacturing precision requirements within practical limits
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 solution enhances the GMR effect, increases the reliability of the magnetic detecting element, and allows for higher track density recording by firmly fixing the magnetization of the pinned magnetic layer, reducing distortion and asymmetry in reproduction waveforms.
Implementation Method 1
a first magnetostriction-enhancing layer made of a nonmagnetic metal, disposed on the surface opposite to the nonmagnetic material layer of the first magnetic layer and a second magnetostriction-enhancing layer made of a nonmagnetic metal, disposed between the second magnetic layer and the nonmagnetic material layer
Implementation Method 2
the magnetization of a pinned magnetic layer is more firmly fixed by the uniaxial anisotropy of the pinned magnetic layer
Implementation Method 3
a multilayer structure defining a pinned layer P or a free layer F, constituted of a magnetic layer FF and a nonmagnetic layer FN produces an electron scattering effect, that is, the resistance at the interface between the magnetic layer FF and the nonmagnetic layer FN has large spin dependency
Implementation Method 4
The antiferromagnetic layer 4 has a specific resistance as high as, for example, about 200 μΩ·cm2 (or more), and generates Joule heat when a current is applied to the electrodes 5 and 6. The Joule heat causes lattice vibration of conduction electrons in the adjacent pinned magnetic layer 3
Data Source
AI summary
A CPP magnetic detecting element having a pinned magnetic layer whose magnetization is fixed by its uniaxial anisotropy in a structure that CIP magnetic detecting elements do not allow. In the CPP magnetic detecting element, the upper and lower surfaces of a pinned magnetic layer is disposed between nonmagnetic metal magnetostriction-enhancing layers. CPP magnetic detecting elements allow this structure without degrading the GMR effect. Thus, the magnetostriction coefficient of the pinned magnetic layer can be increased from above and below to produce an appropriate magnetoelasticity. Consequently, the magnetization of the pinned magnetic layer can be more firmly fixed.