Magnetic Wall Analog Memory Vertical Read Current
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Solution Overview
Problem
Conventional magnetic wall driving MRAMs are unable to stably read analog data due to the requirement of flowing current in the in-plane direction during reading, leading to digital signal output and erroneous data changes.
Innovation Solution
A magnetic wall utilization-analog memory element with a magnetic wall driving layer, a magnetization fixed layer, and a lower electrode layer, where the read current flows vertically, reducing magnetic wall shift during reading and allowing for stable multilevel or analog data reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If current flows in the in-plane direction during reading to shift the magnetic wall, then the magnetic wall driving function is achieved, but the magnetic wall shifts outside the overlap portion causing digital signal output and loss of analog data
Solution Approach 1:
The patent changes the reading current direction from in-plane (horizontal) to vertical direction, perpendicular to the magnetic wall driving direction. This dimensional change allows the reading current to pass through the magnetization fixed layer and magnetic wall driving layer vertically, preventing magnetic wall shift during reading while maintaining the ability to shift the magnetic wall during writing operations in the in-plane direction.
Solution Approach 2:
The patent divides the magnetic wall driving layer into three distinct regions: a first region with first magnetization direction, a second region with second magnetization direction opposite to the first, and a third region between them. This segmentation enables different functional zones where the magnetic wall can be positioned and controlled independently, allowing stable analog data representation through vertical current flow while maintaining magnetic wall shifting capability through in-plane current in specific regions.
2Productivity
If the magnetic wall shifts during reading, then the magnetic wall driving effect is activated, but erroneous data changes occur and initial signal changes are disrupted
Solution Approach 1:
By orienting the reading current in the vertical direction perpendicular to the magnetic wall plane, the patent eliminates the spin transfer torque effect that would otherwise cause magnetic wall shift during reading. This dimensional separation ensures that reading operations do not trigger magnetic wall movement, preventing erroneous data changes while maintaining fast reading speed.
Solution Approach 2:
The patent introduces a magnetization fixed layer as an intermediary between the magnetic wall driving layer and the readout system. This fixed layer provides a stable reference magnetization direction and prevents the reading current from directly interacting with and shifting the magnetic wall, thereby preserving analog data integrity while enabling efficient reading operations.
3Reliability
If current flows vertically through the magnetization fixed layer and magnetic wall driving layer, then magnetic wall shift during reading is prevented, but the reading current path becomes more complex
Solution Approach 1:
The patent merges the reading and writing functions into a single magnetic wall driving layer structure by providing both in-plane current paths for writing and vertical current paths for reading within the same layered configuration. This integration allows the device to perform both operations without requiring separate structural systems, managing complexity while maintaining reliability.
Solution Approach 2:
The magnetic wall driving layer is designed to serve multiple functions: it can receive in-plane current for magnetic wall shifting (writing), receive vertical current for reading operations, and maintain stable magnetization regions for data storage. This multi-functionality reduces the need for separate specialized components, managing device complexity while ensuring reliable analog data reading.
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
Enables stable reading of multilevel or analog data by preventing magnetic wall shift during reading, reducing magnetic noise and allowing for accurate output of resistance changes.
Implementation Method 1
shifts the magnetic wall by the spin transfer effect of spin polarized electrons
Implementation Method 2
a magnetoresistive effect element having a magnetization free layer and a magnetization fixed layer
Data Source
AI summary
A magnetic wall utilization-analog memory element includes a magnetic wall driving layer including a magnetic wall, a first region, a second region, and a third region located between the first region and the second region, a magnetization fixed layer provided at a the third region through a nonmagnetic layer, and a lower electrode layer provided at a position in the third region that overlaps the magnetization fixed layer in plan view on a second surface opposite to a first surface on which the magnetization fixed layer is provided.