Magnetic Memory Cell Using Orthogonal Magnetic Field for Write Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional magnetic memory cells face challenges in reliably writing data within 10 nanoseconds or shorter time frames due to increased threshold current for spin transfer torque magnetization reversal, leading to incorrect writing probabilities that are neither zero nor one.
Innovation Solution
Applying a magnetic field orthogonal to the magnetic easy axis of the ferromagnetic free layer in a magnetic memory cell using a wiring arrangement that generates a spatial magnetic field, reducing the current required for spin transfer torque magnetization reversal and enhancing writing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If spin transfer torque magnetization reversal is used for writing data in 10 nanoseconds or shorter time frames, then writing speed is improved, but threshold current increases significantly leading to incorrect writing probability
Solution Approach 1:
A magnetic field applying wiring is introduced as an intermediary component to generate a spatial magnetic field that assists the spin transfer torque effect. This magnetic field mediator reduces the threshold current requirement for magnetization reversal, enabling reliable writing at high speeds without the excessive current demands of spin transfer torque alone
Solution Approach 2:
The invention changes the physical parameters by applying an external magnetic field in addition to the spin transfer torque. This parameter change (adding magnetic field strength as a control variable) modifies the magnetization reversal condition, allowing the system to achieve both high-speed writing and high reliability by tuning the combined effect of spin torque and magnetic field
2Speed
If higher current is applied to achieve certain magnetization reversal in short time, then writing speed is improved, but power consumption increases
Solution Approach 1:
The magnetic field wiring acts as an intermediary that converts electrical current into a spatial magnetic field, which then assists the magnetization reversal process. This intermediary mechanism reduces the direct current burden on the bit line, lowering power consumption while maintaining high writing speed through the combined spin torque and magnetic field effect
3Device complexity
If spin transfer torque alone is used for magnetization reversal, then device structure is simplified, but writing reliability in short time frames deteriorates
Solution Approach 1:
The magnetic field wiring serves multiple functions: it generates the spatial magnetic field for assisted magnetization reversal, and can be integrated into the existing memory cell structure. This multi-functional approach improves writing reliability without significantly increasing device complexity, as the wiring structure leverages existing architectural elements
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 the probability of incorrect writing and achieves a low-power, highly reliable nonvolatile magnetic memory with reduced write current, enabling efficient data storage in a short time frame.
Implementation Method 1
a high-output tunnel magnetoresistance device
Implementation Method 2
another method is disclosed, for example, in the specification of U.S. Pat. No. 5,695,864, and in Japanese Patent Application Laid-open No. 2002-305337. The disclosed method is known as a spin transfer torque magnetization reversal method, in which, rotation of magnetization is accomplished by passing a current directly through a magnetoresistance device
Implementation Method 3
Japanese Patent Application Laid-open No. 2005-50907 discloses a way of applying a magnetic field, in which a magnetic field is applied in a direction parallel to the magnetic easy axis direction of the ferromagnetic free layer
Data Source
AI summary
To provide a highly-reliable, low-power-consumption nonvolatile memory. A magnetization reversal of a ferromagnetic free layer is accomplished with a spin transfer torque in a state where an appropriate magnetic field is applied in a direction orthogonal to the direction of the magnetic easy axis of the ferromagnetic free layer of the tunnel magnetoresistance device that the magnetic memory cell includes. Preferably, the magnetic field is applied in a direction forming an angle of 45° with the direction perpendicular to the film plane.