Synthetic Storage Layer MRAM for Dipolar Coupling Reduction
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Solution Overview
Problem
MRAM cells face challenges with increasing dipolar coupling between storage and sense layers as the magnetic tunnel junction diameter scales down, leading to higher power consumption and reduced switching efficiency during read operations due to stray fields.
Innovation Solution
A magnetic random access memory (MRAM) element with a synthetic storage layer comprising a first and second ferromagnetic layer and a non-magnetic coupling layer, where the magnetization is adjusted by temperature changes, allowing for easy adjustment at high temperatures and low stray fields at low temperatures, utilizing a thermally-assisted writing method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the magnetic tunnel junction diameter is scaled down to reduce device size, then the area of the magnetic tunnel junction is reduced, but the dipolar coupling between storage and sense layers increases
Solution Approach 1:
The patent changes the temperature parameter to control the magnetization state of the storage layer. At high temperatures, the storage layer magnetization is reduced or reversed, which decreases the dipolar coupling with the sense layer. This allows for scaling down the magnetic tunnel junction area while maintaining acceptable coupling levels during read operations.
Solution Approach 2:
The patent introduces dynamic control of the storage layer magnetization through temperature changes. The magnetization state is not static but can be switched between high and low states depending on temperature, enabling dynamic adjustment of dipolar coupling strength to suit different operational requirements.
2Object-generated harmful factors
If the dipolar coupling is reduced by increasing storage layer magnetization, then the stray field decreases, but the power consumption increases due to higher magnetic fields required for switching
Solution Approach 1:
The patent uses temperature as a control parameter to adjust the storage layer magnetization. By heating the storage layer, the magnetization is reduced, which decreases stray field and dipolar coupling. This thermal control mechanism allows for low power consumption during read operations without requiring high magnetic fields for switching.
Solution Approach 2:
The patent replaces the mechanical approach of using high magnetic fields to control magnetization with a thermal approach. Instead of applying strong magnetic fields to switch magnetization states, the system uses temperature changes to control the storage layer magnetization, thereby reducing the power consumption associated with magnetic field generation.
3Object-generated harmful factors
If the storage layer magnetization is increased to reduce stray field, then the magnetic flux configuration is improved, but the switching speed decreases due to higher coercive field requirements
Solution Approach 1:
The patent introduces dynamic control of storage layer magnetization through temperature changes. The magnetization state can be switched between high and low states depending on temperature, enabling dynamic adjustment of dipolar coupling strength to suit different operational requirements.
Solution Approach 2:
The patent changes the temperature parameter to control the magnetization state of the storage layer. At high temperatures, the storage layer magnetization is reduced or reversed, which decreases the dipolar coupling with the sense layer. This thermal control mechanism allows for low power consumption during read operations without requiring high magnetic fields for switching.
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 approach reduces dipolar coupling, enabling efficient read and write operations with lower power consumption and smaller magnetic tunnel junctions by minimizing stray fields at read temperatures and optimizing magnetization switching with reduced magnetic fields.
Implementation Method 1
the magnetization is adjusted by temperature changes, allowing for easy adjustment at high temperatures and low stray fields at low temperatures
Implementation Method 2
a dipolar coupling between the storage and sense layers occurs due to local magnetic stray field, coupling the magnetization of the sense layer with the one of the storage layer
Data Source
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AI summary
The present disclosure concerns a random access memory (MRAM) element (1) comprising a magnetic tunnel junction (2) composing: a storage layer (23); a sense layer (21); and a tunnel barrier layer (22) included between the storage layer (23) and the sense layer (21); the storage layer (23) comprising: a first magnetic layer (231) having a first storage magnetization (234); a second magnetic layer (232) having a second storage magnetization (235); and a non-magnetic coupling layer (233) separating the first and second magnetic layers (231, 232) such that the first storage magnetization (234) is substantially antiparallel to the second storage magnetization (235); the first and second magnetic layers (231, 232) being arranged such that: at a read temperature (T1) the first storage magnetization (234) is substantially equal to the second storage magnetization (235); and at a write temperature (T2, T3, T4) which is higher than the read temperature (T1) the second storage magnetization (235) is larger than the first storage magnetization (234). The disclosed MRAM element generates a low stray field when the magnetic tunnel junction is cooled at a low temperature.