CPP Magnetoresistive Element Spacer Layer Optimization
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Solution Overview
Problem
Current CPP-type GMR elements face challenges in achieving high enough MR ratios for next-generation magnetic recording densities, particularly for 1 Tbits/in^2, where the area resistivity needs to be lower than 0.3Ω·μm^2 to maintain signal quality and noise ratio.
Innovation Solution
Incorporating a spacer layer with a nonmagnetic metal layer, a semiconductor oxide layer of zinc oxide, and ferromagnetic layers containing nitrogen, carbon, or oxygen, specifically CoFe, to optimize the magnetic properties and reduce area resistivity, while maintaining a high MR ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the element size is reduced to achieve higher recording density (1 Tbits/in^2), then the recording density is improved, but the resistance value increases and MR ratio becomes insufficient
Solution Approach 1:
The patent changes the material parameters of the spacer layer by introducing a semiconductor oxide layer (ZnO, MgO, SiO2, etc.) with controlled thickness (0.5-5 nm) and conductivity. This parameter change allows the spacer layer to provide both magnetic isolation and controlled electrical conductivity, enabling high MR ratio even in miniaturized elements for 1 Tbits/in^2 recording density
Solution Approach 2:
The patent employs composite material structure in the spacer layer by combining semiconductor oxide materials with specific conductivity characteristics. This composite approach creates a spacer layer that simultaneously provides magnetic isolation between ferromagnetic layers and controlled electrical resistance, resolving the contradiction between element miniaturization and MR ratio maintenance
2Reliability
If the area resistivity is reduced to maintain signal quality, then the signal-to-noise ratio is improved, but the MR ratio becomes insufficient for high-density recording
Solution Approach 1:
The patent applies local quality by creating a spacer layer with spatially varying electrical properties through the use of semiconductor oxide materials. The spacer layer has different conductivity characteristics in different regions, allowing localized control of current flow and spin scattering, thereby achieving both low area resistivity for good SN ratio and high MR ratio for precise magnetic field detection
Solution Approach 2:
The patent changes the electrical conductivity parameter of the spacer layer by selecting semiconductor oxide materials with appropriate band gaps and carrier concentrations. This parameter optimization enables the spacer to provide low resistance paths for charge current while maintaining high spin-dependent scattering, simultaneously improving SN ratio and MR ratio
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 proposed structure achieves an improved MR ratio and reduced area resistivity, enhancing the sensitivity and output characteristics of the CPP-type GMR elements, suitable for high-density magnetic recording applications.
Implementation Method 1
ZnO is generally known as an N-type semiconductor characteristic because of the existence of zinc as an interstitial atom and an electron emitted from an oxygen deficiency
Implementation Method 2
A magnetoresistive effect element in a current perpendicular to plane type (CPP-type) structure that detects a magnetic field intensity as a signal from a magnetic recording medium
Implementation Method 3
The magnetization direction of the first ferromagnetic layer can be pinned by making an antiferromagnetic layer adjacent thereto and providing unidirection anisotropic energy (also referred to as 'exchange bias' or 'coupling magnetic field') to the first ferromagnetic layer by means of exchange-coupling between the antiferromagnetic layer and the first ferromagnetic layer
Implementation Method 4
A spin valve type CPP-GMR element includes a laminated structure having a conductive nonmagnetic intermediate layer, and a first ferromagnetic layer and a second ferromagnetic layer, which are separated by the conductive nonmagnetic intermediate layer
Data Source
AI summary
An MR element according to the present invention has the superior effects that further improve an MR ratio because a structure of a spacer layer 40 is configured of a certain three-layer structure with certain materials, and at least one of a first ferromagnetic layer 30 and a second ferromagnetic layer 50 contains a certain amount of an element selected from the group of nitrogen (N), carbon (C), and oxygen (O).