Dual-Track Magnetic Memory with Spacer Isolation for Stable Reads
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Solution Overview
Problem
Existing magnetic memory devices with racetrack structures face challenges in maintaining a stable motion of magnetic domain walls, achieving high integration, and ensuring long lifetime, particularly due to potential damage to tunnel barrier layers under high voltage applications.
Innovation Solution
The magnetic memory device incorporates a spacer layer with an insulating material between the lower and upper magnetic track layers, which electrically disconnects the upper track layer from the lower track layer driven by high voltage, thereby preventing tunnel barrier breakdown. This design allows for the copying of magnetization directions based on leakage magnetic fields, enabling stable operation without applying high voltage to the upper track layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If high voltage is applied to drive magnetic domain wall motion in the lower track layer, then magnetic memory operation is enabled, but tunnel barrier breakdown occurs reducing device lifetime
Solution Approach 1:
The magnetic track structure is segmented into two separate layers: a lower track layer for writing operations and an upper track layer for reading operations. This segmentation allows independent voltage application to each layer, enabling high voltage to be applied only to the lower layer during writing while the upper layer remains at low voltage during reading, thus preventing tunnel barrier breakdown and extending device lifetime
Solution Approach 2:
A spacer layer is introduced as an intermediary between the lower and upper magnetic track layers. This spacer layer provides both electrical isolation to prevent voltage-induced damage to the tunnel barrier and magnetic coupling through leakage fields to enable magnetization copying from the lower to upper layer, resolving the contradiction between enabling high-voltage operation and preventing tunnel barrier damage
2Device complexity
If the upper magnetic track layer is electrically connected to the lower track layer, then simplified structure is achieved, but tunnel barrier breakdown occurs under high voltage
Solution Approach 1:
The spacer layer serves as an intermediary that provides electrical isolation between the upper and lower track layers, preventing direct voltage transmission that would cause tunnel barrier breakdown. Simultaneously, it maintains magnetic coupling through leakage fields, achieving both structural simplicity and tunnel barrier protection
Solution Approach 2:
The spacer layer is strategically positioned only where needed for electrical isolation and magnetic coupling between specific regions of the upper and lower track layers. This localized approach maintains structural simplicity while providing targeted protection to the tunnel barrier in critical regions
3Reliability
If a spacer layer is introduced to electrically disconnect the track layers, then tunnel barrier protection is achieved, but device structure becomes more complex
Solution Approach 1:
The spacer layer is designed to perform multiple functions simultaneously: electrical isolation to protect the tunnel barrier, magnetic coupling through leakage fields for data copying, and structural support between layers. This multi-functionality justifies the added structural complexity by delivering comprehensive protection and operational capability in a single component
4Quantity of substance
If magnetization directions of upper and lower track layers are anti-parallel at overlapping positions, then higher storage density is achieved, but read operation reliability decreases
Solution Approach 1:
Instead of having anti-parallel magnetization directions between upper and lower track layers at overlapping positions, the invention inverts this arrangement to have parallel magnetization directions. This inversion improves read operation reliability by ensuring consistent magnetic field interactions between layers, while storage capacity is maintained through the racetrack topology and domain wall motion mechanism
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 configuration enhances the stability and longevity of the magnetic memory device by preventing tunnel barrier breakdown, allowing for infinite read operations theoretically, and maintaining high integration and performance.
Implementation Method 1
the operation magnetic track layer and the copy magnetic track layer have magnetization directions parallel to each other at positions overlapping each other in the first direction, based on a leakage magnetic field of the operation magnetic track layer
Implementation Method 2
a spin hall conductive layer, an operation magnetic track layer and a copy magnetic track layer, stacked in a first direction on the spin hall conductive layer
Data Source
AI summary
A magnetic memory device includes a lower magnetic track layer extending in a first direction and including a plurality of first magnetic domains, a spacer layer on the lower magnetic track layer and extending in the first direction, an upper magnetic track layer on the spacer layer and extending in the first direction, the upper magnetic track layer including a plurality of second magnetic domains, and a plurality of read units on the upper magnetic track layer and arranged apart from one another in the first direction, wherein the plurality of first magnetic domains and the plurality of second magnetic domains have magnetization directions parallel to each other at positions overlapping each other in a second direction perpendicular to the first direction.