Magnetoresistive Sense Layer Segmentation for TMR Temperature Compensation
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Solution Overview
Problem
Conventional magnetoresistive elements exhibit a significant negative temperature coefficient of sensitivity (TCS) due to the temperature dependence of tunnel magnetoresistance (TMR) and magnetic susceptibility, limiting their accuracy and potential applications.
Innovation Solution
A magnetoresistive element with a ferromagnetic sense layer comprising a first and second portion, where the magnetic coupling and perpendicular magnetic anisotropy (PMA) are adjusted to shift the TCS positively, compensated by a mediation layer and dilution of the sense layer magnetization, reducing the temperature dependence of TMR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a vortex configuration is used in the sense layer to achieve linear and non-hysteretic behavior, then the sensor performance is improved, but the temperature coefficient of TMR becomes large and negative, limiting accuracy
Solution Approach 1:
The sense layer is divided into a first sense layer portion and a second sense layer portion. The first portion is configured to allow for a vortex state, while the second portion is configured to stabilize the vortex configuration. This segmentation enables the sensor to maintain linear and non-hysteretic behavior while reducing the temperature coefficient of TMR, thereby improving both measurement precision and reliability across varying temperatures.
2Stability of the object's composition
If the sense layer is designed to maintain vortex stability, then the linear response is improved, but the TMR diminishes with temperature increase, reducing accuracy
Solution Approach 1:
The sense layer is divided into a first sense layer portion and a second sense layer portion. The first portion is configured to allow for a vortex state, while the second portion is configured to stabilize the vortex configuration. This segmentation enables the sensor to maintain linear and non-hysteretic behavior while reducing the temperature coefficient of TMR, thereby improving both measurement precision and reliability across varying temperatures.
Solution Approach 2:
The magnetoresistive element uses a composite structure with the sense layer comprising two distinct portions with different configurations. The first portion facilitates vortex formation while the second portion stabilizes it, creating a composite structure that maintains both vortex stability and acceptable TMR characteristics across temperature ranges.
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 achieves a high degree of TCS compensation with minimal modification, maintaining linear and non-hysteretic behavior, enhancing the element's accuracy and applicability across varying temperatures.
Implementation Method 1
The difference between the value of the high and low resistance (RAP−RP) is also known as the tunnel magnetoresistance (TMR).
Implementation Method 2
a perpendicular magnetic anisotropy (PMA) originating from the interface between the first sense layer portion and the tunnel barrier layer is between 8×10^4 A/m and 8×10^5 A/m
Data Source
AI summary
A magnetoresistive element comprising a reference layer, a ferromagnetic sense layer having a free sense magnetization, and a tunnel barrier layer between the reference layer and the sense layer. The sense layer comprises a first sense layer portion in contact with the tunnel barrier layer and a second sense layer portion in contact with the first sense layer portion. The first sense layer portion is configured such that a magnetic coupling between the first and second sense layer portions is between ±10−4 J/m2 and ±10−3 J/m2; and a perpendicular magnetic anisotropy (PMA) originating from the interface between the first sense layer portion and the tunnel barrier layer is between 8×104 A/m and 8×105 A/m, such as to shift positively the TCS of the magnetoresistive element and compensate the negative temperature coefficient of TMR of the magnetoresistive element.