Magnetic Domain Wall Data Storage Device Design
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Solution Overview
Problem
Conventional data storage devices using magnetic domain wall movement face limitations in writing operations due to magnetic layer properties and dimensions, particularly with thick layers and the risk of etching damage affecting separation layer properties, which restricts recording density and fabrication complexity.
Innovation Solution
A data storage device design where a first magnetic layer with adjustable domain widths and a second magnetic layer are used, allowing for current-controlled magnetic domain wall movement without requiring a stack structure, thus avoiding etching damage and enabling flexible recording across varying magnetic layer properties and dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the magnetic layer is increased to enable perpendicular magnetic recording, then the recording density and storage capacity are improved, but the writing operation becomes difficult to perform using conventional spin torque methods
Solution Approach 1:
The patent transitions from in-plane magnetization to perpendicular magnetization, changing the dimension of magnetic moment orientation. This enables the use of thicker magnetic layers (100 nm or more) while maintaining recording capability, as the perpendicular magnetic anisotropy allows for stable magnetization in the thickness direction, overcoming the limitation of conventional spin torque methods that were restricted to thin layers.
Solution Approach 2:
The patent changes the magnetic anisotropy parameter from in-plane to perpendicular by adjusting the magnetic layer composition and structure. This parameter change enables the magnetic layer to maintain stable magnetization at greater thicknesses, allowing writing operations to be performed on thicker layers that provide higher recording density.
2Ease of operation
If a stack structure with separation layer is used for TMR or GMR write head, then the writing operation capability is improved, but the separation layer surface may be damaged by etching, deteriorating the writing operation properties
Solution Approach 1:
The patent extracts and eliminates the separation layer from the write head structure. By using a magnetic domain wall movement mechanism that does not require a TMR or GMR stack structure, the separation layer is removed entirely, preventing etching damage to this critical component while maintaining writing operation capability through direct magnetic field application.
Solution Approach 2:
The patent uses a simplified write head structure that copies only the essential magnetic field generation capability without replicating the complex TMR/GMR stack structure. This alternative approach achieves writing functionality through magnetic domain wall movement driven by external magnetic fields, avoiding the need for a damaged separation layer.
3Manufacturing precision
If multi-layer thin film processes are used to form TMR or GMR write head, then the writing operation precision is improved, but the fabrication complexity increases significantly
Solution Approach 1:
The patent extracts and removes the complex multi-layer thin film stack structure from the write head design. By eliminating the TMR or GMR stack structure, the number of fabrication steps is dramatically reduced, while the essential writing function is maintained through a simpler magnetic field-based domain wall movement mechanism.
Solution Approach 2:
Instead of using a complex stack structure to achieve writing precision, the patent inverts the approach by using a simplified structure with externally applied magnetic fields. This inversion reduces fabrication complexity while maintaining writing capability through direct magnetic domain manipulation.
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 allows for high-density data storage without deteriorating operational characteristics, enabling efficient recording and reading operations across different magnetic layer thicknesses and properties, and simplifies the fabrication process by eliminating the need for complex multi-layer structures.
Implementation Method 1
A magnetic domain wall is a boundary portion between magnetic domains having different magnetization directions. The magnetic domain wall can be moved by an external magnetic field or by a current applied to a magnetic substance.
Implementation Method 2
The method using the spin torque phenomenon of electrons can be classified into a method using a giant magneto resistance (GMR) and a method using a tunnel magneto resistance (TMR).
Implementation Method 3
when magnetic domains pass through a read/write head by movement of the magnetic domain wall, an operation of reading/writing data is possible
Data Source
Figure 1~2A
Figure 2B~2C
Figure 2D
AI summary
Provided are a data storage device using magnetic domain wall movement and a method of operating the data storage device. The data storage device includes a first magnetic layer for writing data having two magnetic domains magnetized in opposite directions to each other and a second magnetic layer for storing data formed on at least one side of the first magnetic layer. The data storage device may further include a data recording device connected to both ends of the first magnetic layer and the end of the second magnetic layer which is not adjacent to the first magnetic layer, a read head formed a predetermined distance from the end of the second magnetic layer which is not adjacent to the first magnetic layer, and a current detector connected to the read head and the data recording device.