Magnetic Tunnel Junction Shape Anisotropy Thermal Stability
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Solution Overview
Problem
Magnetic tunnel junctions with out-of-plane magnetization in prior art face challenges in reducing thermal variations of magnetic anisotropy over a wide temperature range, managing sufficient thermal stability at advanced technological nodes, and minimizing writing current, especially during soldering processes and in applications requiring low power consumption.
Innovation Solution
A magnetic tunnel junction design with a storage layer thickness between 0.8 and 8 times a characteristic planar dimension, where the shape anisotropy contribution is at least two times greater than interfacial anisotropy contributions, and using materials with high Curie temperatures to reduce thermal variations and Gilbert dampening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the storage layer thickness is increased to enhance thermal stability, then the thermal stability improves, but the writing current increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the storage layer thickness within a specific range (0.8 to 8 times the characteristic planar dimension) and adjusting the ratio between shape anisotropy and interfacial anisotropy contributions. This optimization allows achieving sufficient thermal stability while keeping the writing current at acceptable levels, resolving the contradiction between thermal stability and writing current.
Solution Approach 2:
The patent employs composite material structures by combining the storage layer with specific tunnel barrier materials and reference layers, where the shape anisotropy and interfacial anisotropy work together in a composite manner. This composite approach enables the system to achieve both thermal stability and low writing current by leveraging the synergistic effects of different material contributions to anisotropy.
2Reliability
If the shape anisotropy contribution is increased to reduce thermal variations, then the thermal stability improves, but the device complexity increases
Solution Approach 1:
The patent uses parameter changes by adjusting the storage layer thickness and geometric characteristics to control the shape anisotropy contribution ratio. By setting the shape anisotropy contribution to be at least two times greater than interfacial anisotropy contributions through parameter optimization rather than structural complexity, the patent achieves thermal stability while minimizing device complexity.
3Use of energy by moving object
If the storage layer thickness is reduced to minimize writing current, then the writing current decreases, but the thermal stability deteriorates
Solution Approach 1:
The patent applies parameter changes by defining an optimal thickness range for the storage layer (0.8 to 8 times the characteristic planar dimension) that balances thermal stability and writing current. Within this range, the shape anisotropy contribution dominates, providing sufficient thermal stability while keeping the writing current at acceptable levels, thus resolving the contradiction between these two parameters.
4Reliability
If the interfacial anisotropy contribution is increased to improve thermal stability, then the thermal stability improves, but the variation of temperature memory point increases
Solution Approach 1:
The patent uses parameter changes by controlling the ratio between shape anisotropy and interfacial anisotropy contributions, setting the shape anisotropy to be at least two times greater. This parameter optimization reduces the relative impact of interfacial anisotropy variations with temperature, thereby minimizing temperature memory point variation while maintaining adequate thermal stability.
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 design enhances thermal stability and reduces writing current variability, allowing for reliable memory retention across a wide temperature range and lower power consumption, particularly beneficial for automotive, industrial, and consumer electronics applications.
Implementation Method 1
the perpendicular magnetic anisotropy mainly induced by the shape of the variable magnetisation layer
Implementation Method 2
Tunnel magnetoresistance (TMR) is defined as being the ratio TMR=(Rmax−Rmin)/Rmin
Data Source
AI summary
A magnetic tunnel junction with out-of-plane magnetisation includes a storage layer; a reference layer; and a tunnel barrier layer. The two magnetisation states of the storage layer are separated by an energy barrier including a contribution due to the shape anisotropy of the storage layer and a contribution of interfacial origin for each interface of the storage layer. The storage layer has a thickness comprised between 0.8 and 8 times a characteristic dimension of a planar section of the tunnel junction. The contribution to the energy barrier due to the shape anisotropy of the storage layer is at least two times greater and preferably at least 4 times greater than the contributions to the energy barrier of interfacial origin.