Quadruple-Interface MR Element for High TMR and Low RA
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Solution Overview
Problem
Existing magnetoresistance effect elements with a quadruple interface face challenges in maintaining high thermal stability index Δ and magnetoresistance ratio while minimizing resistance area product RA and element size, as reducing film thickness affects these characteristics.
Innovation Solution
A magnetoresistance effect element with a quadruple interface configuration, where the first divided recording layer has a higher Co/Fe ratio than the second, and the second divided recording layer has a higher effective magnetic anisotropy energy density, optimized through controlled composition and film formation methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the number of interfaces in contact with the recording layer is increased to increase the thermal stability index, then the interfacial magnetic anisotropy energy density is improved, but the resistance area product increases
Solution Approach 1:
The recording layer is divided into two separate recording layers (first recording layer and second recording layer), each in contact with junction layers. This segmentation allows each recording layer to contribute to interfacial magnetic anisotropy energy density while maintaining controlled resistance area product through optimized individual layer thicknesses and compositions.
Solution Approach 2:
Different regions of the magnetoresistance effect element are given different compositions and properties. The first and second recording layers have different thicknesses and material compositions, allowing optimization of interfacial magnetic anisotropy at each interface while controlling the overall resistance area product through local property variation.
2Area of stationary object
If the element size is miniaturized to reduce the cell area, then the cell capacity is improved, but the effective magnetic anisotropy energy density decreases
Solution Approach 1:
The patent transitions from a single-interface configuration to a multi-interface configuration by stacking multiple junction layers and recording layers vertically. This dimensional change allows the system to maintain high effective magnetic anisotropy energy density through increased interfacial area in the vertical dimension while keeping the horizontal cell area small for high capacity.
Solution Approach 2:
The magnetoresistance effect element uses composite structures with multiple materials including different recording layers, junction layers, and barrier layers. This composite approach enables optimization of magnetic properties at each interface to maintain high effective magnetic anisotropy energy density even when the overall element size is reduced for increased cell capacity.
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
Achieves a high magnetoresistance ratio and effective magnetic anisotropy energy density while reducing the resistance area product RA, enabling smaller element size and improved thermal stability.
Implementation Method 1
Bit information recorded in a magnetic layer (recording layer) of the MRAM is transmitted through the tunnel barrier layer and is read using the effect of a tunnel magnetoresistance (TMR).
Implementation Method 2
by increasing the number of interfaces in contact with the recording layer, the interfacial magnetic anisotropy energy density Ki is increased
Data Source
AI summary
A magnetoresistance effect element includes a first reference layer, a first junction layer, a first divided recording layer, a second junction layer, a second divided recording layer, and a third junction layer. The first divided recording layer has a configuration having a high magnetoresistance ratio (MR ratio), and the second divided recording layer (3) has a configuration having a high effective magnetic anisotropy energy density (Kefft).