Spin-Injection MRAM with Assist Magnetic Field
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Solution Overview
Problem
The existing spin-injection magnetization reversal process for magnetic random access memory requires high current densities, which can lead to destruction of the tunnel barrier layer during miniaturization, and results in high power consumption and limited memory capacity due to the need for large driver and sinker areas.
Innovation Solution
A spin-injection magnetic random access memory that uses an assist magnetic field in the direction of hard magnetization to reduce the required spin-injection current, allowing for smaller current values and more efficient writing operations by separating or partially overlapping the paths of the spin-injection and assist currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high current density spin-injection is used for magnetization reversal, then writing capability is achieved, but tunnel barrier layer destruction occurs and power consumption increases
Solution Approach 1:
A magnetic field application unit is introduced as an intermediary component between the spin-injection current source and the magnetic recording layer. This unit applies an assist magnetic field in the hard magnetization direction to facilitate magnetization reversal, allowing the spin-injection current to operate at lower densities that prevent tunnel barrier layer destruction while maintaining reliable writing capability.
Solution Approach 2:
The invention changes the operational parameters by applying an assist magnetic field that modifies the magnetization reversal process. By superimposing a magnetic field in the hard magnetization direction, the required spin-injection current density is reduced from destructive levels to safe levels that preserve the tunnel barrier layer integrity.
2Reliability
If high current density is used for writing, then magnetization reversal is achieved, but power consumption increases
Solution Approach 1:
The magnetic field application unit serves as a mediator that reduces the energy burden on the spin-injection current. By providing an assist magnetic field that promotes magnetization reversal, the required current density is reduced, thereby lowering power consumption while maintaining reliable magnetization reversal.
3Device complexity
If only spin-injection current is used for writing, then device structure is simple, but driver and sinker areas become large
Solution Approach 1:
The magnetic field application unit is designed to be integrated with existing memory cell structures, allowing it to perform multiple functions: providing assist magnetic field during writing, and potentially serving as part of the read path or cell selection mechanism. This multi-functionality reduces the need for separate large-area driver and sinker circuits.
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 enables stable write operations with reduced spin-injection currents, minimizing tunnel barrier layer destruction and lowering power consumption while allowing for smaller memory cell sizes and increased memory capacity.
Implementation Method 1
spin-polarized electrons (spin-injection currents) are injected into the magnetic recording layer of the memory element to thereby reverse the magnetization of the magnetic recording layer
Implementation Method 2
applies, to the magnetoresistive element, a magnetic field of a direction of a hard magnetization
Data Source
AI summary
A spin-injection magnetic random access memory of an aspect of the present invention includes a magnetoresistive element, a unit which writes data into the magnetoresistive element by use of spin-polarized electrons generated by a spin-injection current and which applies, to the magnetoresistive element, a magnetic field of a direction of a hard magnetization of the magnetoresistive element during the writing.