Spin-Orbit Torque Wire Voltage Control for Magnetic Memory
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Solution Overview
Problem
In magnetic memories, spin-orbit torque-type magnetoresistance effect elements face challenges in maintaining a low write error rate when applying voltages above a certain threshold, leading to unstable data writing due to electrical breakdown concerns.
Innovation Solution
A data writing method and magnetic memory system that utilize a spin-orbit torque wire with a voltage applied in a specific direction, within critical and predetermined limits, to ensure stable data writing across varying temperatures, by setting the voltage to be between 1.01 and 1.65 times the critical writing voltage at 20°C, depending on temperature, to maintain a write error rate below 10^-7.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large writing current is passed through the spin-orbit torque wire to decrease the write error rate, then the write error rate decreases, but the voltage may exceed the breakdown voltage causing electrical breakdown
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the writing voltage based on temperature conditions. The voltage is set to different ranges depending on whether the temperature is below or above 20°C, optimizing the balance between achieving sufficient write error rate reduction and preventing electrical breakdown. This resolves the contradiction by changing the operating voltage parameter according to environmental conditions.
Solution Approach 2:
The patent implements dynamics by making the writing voltage adaptive rather than fixed. The voltage selection changes based on real-time temperature conditions, allowing the system to dynamically optimize between write reliability and device safety. This dynamic approach enables the system to prevent electrical breakdown while maintaining low write error rates across varying operating conditions.
2Reliability
If the writing voltage is increased above the critical writing voltage to ensure reliable data writing, then data writing reliability improves, but the risk of electrical breakdown increases
Solution Approach 1:
The patent changes the voltage parameter based on temperature conditions to resolve the contradiction between writing reliability and device longevity. By setting voltage to specific ranges (1.05-1.30 times critical voltage below 20°C, 1.01-1.20 times above 20°C), the system achieves reliable writing without excessive voltage stress that would reduce service life.
Solution Approach 2:
The patent applies beforehand cushioning by pre-establishing voltage limits that prevent electrical breakdown before it occurs. The predetermined voltage ranges act as protective boundaries that cushion against the harmful effects of excessive voltage, ensuring the magnetoresistance effect elements operate within safe limits while maintaining writing reliability.
3Ease of operation
If a fixed writing voltage is used regardless of temperature, then the device operation is simple, but the write error rate varies with temperature causing unstable data writing
Solution Approach 1:
The patent implements dynamics by transitioning from fixed voltage to temperature-adaptive voltage control. The system automatically adjusts the writing voltage range based on detected temperature conditions, ensuring stable write error rates across different operating temperatures while maintaining relatively simple operation through automated control.
Solution Approach 2:
The patent applies feedback by using temperature information to determine the appropriate writing voltage range. This feedback mechanism ensures that the voltage applied is always appropriate for the current thermal conditions, maintaining writing reliability without requiring complex manual adjustment procedures.
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 method allows for stable data writing in magnetic memories by controlling the voltage applied to the spin-orbit torque wire, ensuring reliable data recording across different environmental temperatures without causing electrical breakdown, thus extending the lifespan of the magnetoresistance effect elements.
Implementation Method 1
An SOT is induced by a pure spin current generated by the spin-orbit interaction or by the Rashba effect at the interface between different materials
Implementation Method 2
An SOT is induced by a pure spin current generated by the spin-orbit interaction or by the Rashba effect at the interface between different materials
Implementation Method 3
a giant magneto-resistance (GMR) device formed of a multi-layer film including a ferromagnetic layer and a non-magnetic layer
Implementation Method 4
a tunneling magneto-resistance (TMR) device in which an insulating layer (a tunneling barrier layer, a barrier layer) is used for a non-magnetic layer
Data Source
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AI summary
A data writing method according to an aspect of the present invention is configured such that a spin-orbit torque-type magnetoresistance effect element includes: a spin-orbit torque wire extending in a first direction; and a functional portion having a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer stacked on one surface of the spin-orbit torque wire in that order from the spin-orbit torque wire, wherein a voltage applied in the first direction of the spin-orbit torque wire is equal to or higher than a critical writing voltage at an environmental temperature and is equal to or lower than a predetermined value. A resistance of the spin orbit torque wire is converted to a temperature of the spin-orbit torque wiring , and a voltage that the voltage source (20) applies to the spin-orbit torque wiring (2) is determined on the basis of the converted temperature of the spin-orbit torque wiring.