Magnetoresistance Effect Element With Segmented Magnetic Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Miniaturization of magnetoresistance effect elements for high-density MRAMs leads to bit information loss due to thermal disturbances, requiring a higher thermal stability factor Δ to ensure nonvolatility of recorded data for 10 years.
Innovation Solution
A magnetoresistance effect element with a first magnetic layer having a Fe composition of 50% or higher and a second magnetic layer with a lower Fe composition, along with a non-magnetic insertion layer, is used to enhance the thermal stability factor Δ by adjusting the interfacial and bulk magnetic anisotropy energies, and optimizing the sputtering gas ratios to maintain perpendicular magnetic anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnetoresistance effect elements are miniaturized to achieve high-density MRAMs, then storage density is improved, but thermal stability factor Δ decreases causing bit information loss
Solution Approach 1:
The patent applies local quality by creating distinct magnetic layers with different Fe compositions - the first magnetic layer has high Fe composition (50% or higher) to generate strong interfacial perpendicular magnetic anisotropy at the MgO interface, while the second magnetic layer has lower Fe composition to provide bulk magnetic anisotropy. This spatial differentiation of material properties enables simultaneous achievement of high thermal stability and miniaturization.
Solution Approach 2:
The patent employs composite materials by combining multiple magnetic layers with different compositions (CoFeB, CoFe, etc.) and a non-magnetic insertion layer (Ta, W, Mo, etc.). This composite structure allows the system to leverage both interfacial magnetic anisotropy from the MgO-high Fe layer interface and bulk magnetic anisotropy from the lower Fe composition layer, achieving thermal stability factor Δ ≥ 70 even in miniaturized elements.
2Strength
If the first magnetic layer has high Fe composition to increase interfacial magnetic anisotropy, then perpendicular magnetic anisotropy is improved, but saturation magnetization increases requiring higher write current
Solution Approach 1:
The patent localizes the high Fe composition (50% or higher) specifically in the first magnetic layer that interfaces with MgO, where it is needed to maximize interfacial perpendicular magnetic anisotropy. The second magnetic layer uses lower Fe composition to reduce saturation magnetization and thus write current requirements. This localized optimization resolves the contradiction between strong anisotropy and low write current.
Solution Approach 2:
The patent segments the magnetic recording layer into two distinct magnetic layers with different Fe compositions. The first layer (adjacent to MgO) has high Fe for strong interfacial anisotropy, while the second layer has lower Fe for reduced saturation magnetization. This segmentation allows independent optimization of anisotropy strength and write current requirements.
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 magnetoresistance effect element with increased thermal stability and tunnel magnetoresistance ratio, enabling high-density MRAMs to retain bit information for an extended period while maintaining high performance.
Implementation Method 1
a magnetization direction of the first magnetic layer (2) being oriented in a perpendicular direction with respect to a film surface due to interfacial perpendicular magnetic anisotropy on an interface with the first non-magnetic layer (1)
Implementation Method 2
A resistance value of the magnetoresistance effect element decreases when the magnetization direction of the magnetic layer of the reference layer and the magnetization direction of the magnetic layer of the recording layer are parallelly arranged but increases when the magnetization directions are arranged antiparallelly
Data Source
AI summary
The present invention provides a magnetoresistance effect element which has a high thermal stability factor Δ and in which a magnetization direction of a recording layer is a perpendicular direction with respect to a film surface, and a magnetic memory including the same. Magnetic layers of a recording layer of the magnetoresistance effect element are divided into at least two, and an Fe composition with respect to a sum total of atomic fractions of magnetic elements in each magnetic layer is changed before stacking the magnetic layers.