Magnetic Memory Element Thermal Agitation Resistance
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Solution Overview
Problem
Magnetic random access memory (MRAM) devices face challenges in suppressing misoperations due to thermal agitation, which affects the reliability and retention time of stored data.
Innovation Solution
A magnetic memory element is designed with a first and second ferromagnetic layer, where the second layer has a portion with a lower magnetic resonance frequency, and a rotating magnetic field is generated to orient the magnetization in response to current flow, enhancing thermal agitation resistance and reducing misoperations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional magnetic tunnel junction (MTJ) element is used for data storage, then the device achieves high-speed operation and large capacity, but thermal agitation causes misoperations that reduce reliability and retention time
Solution Approach 1:
The second ferromagnetic layer is divided into two distinct portions: a first portion with higher magnetic resonance frequency and a second portion with lower magnetic resonance frequency. This segmentation allows each portion to contribute differently to the overall magnetic stability, with the lower frequency portion providing enhanced resistance against thermal agitation while maintaining the high-speed characteristics of the conventional MTJ structure.
Solution Approach 2:
Different portions of the second ferromagnetic layer are assigned different magnetic resonance frequencies through local compositional or structural variations. The first portion maintains properties suitable for high-speed operation, while the second portion is optimized with lower magnetic resonance frequency to specifically counteract thermal agitation effects, creating localized quality enhancement where needed.
2Reliability
If the magnetic resonance frequency of the second ferromagnetic layer is reduced to increase thermal agitation resistance, then misoperations are suppressed, but the current required for writing operations may increase
Solution Approach 1:
By segmenting the second ferromagnetic layer into two portions with different magnetic resonance frequencies, the patent achieves enhanced thermal stability without requiring a uniform reduction in frequency across the entire layer. The lower frequency second portion provides thermal agitation resistance, while the first portion maintains optimal characteristics for efficient writing operations, thereby balancing retention and energy consumption.
Solution Approach 2:
The patent optimizes the magnetic resonance frequency parameter by creating a distribution of frequencies within the second ferromagnetic layer. Rather than using a single frequency value, the layer incorporates regions with different frequencies, allowing the system to achieve both high thermal stability and efficient writing current characteristics through parameter optimization.
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 effectively increases the thermal agitation resistance and reduces misoperations in MRAM devices, improving memory retention time and reducing the current required for writing operations.
Implementation Method 1
A rotating magnetic field is generated by a precession of the magnetization of the third ferromagnetic layer when a current flows in the first stacked unit and the second stacked unit
Implementation Method 2
A rotating magnetic field is generated by a precession of the magnetization of the third ferromagnetic layer when a current flows
Implementation Method 3
The direction of the magnetization of the first portion and the direction of the magnetization of the second portion is oriented in a direction corresponding to an orientation of the current due to actions of the rotating magnetic field and spin-polarized electrons
Implementation Method 4
a data storage unit that uses a magnetic tunnel junction (MTJ) element that exhibits a tunneling magnetoresistive (TMR) effect
Data Source
AI summary
A magnetic memory element includes a first stacked unit and a second stacked unit. The first stacked unit includes a first ferromagnetic layer, a second ferromagnetic layer, and a first nonmagnetic layer. The second ferromagnetic layer is stacked with the first ferromagnetic layer. The second ferromagnetic layer has a first and second portion. The first and second portion has a changeable direction of magnetization. The second portion is stacked with the first portion in a stacking direction of the first ferromagnetic layer and the second ferromagnetic layer. A magnetic resonance frequency of the second portion is lower than a magnetic resonance frequency of the first portion. The first nonmagnetic layer is provided between the first ferromagnetic layer and the second ferromagnetic layer. The second stacked unit is stacked with the first stacked unit in the stacking direction. The second stacked unit includes a third ferromagnetic layer.