Magnetic Domain Wall Memory Cell Without Fixed Layers
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Solution Overview
Problem
The manufacturing process of magnetic domain wall displacement MRAMs is complicated due to the need for fixed layers, which can damage the recording layer and increase write current values due to leakage magnetic fields.
Innovation Solution
A magnetic domain wall displacement memory cell configuration that eliminates the need for fixed layers by using a recording layer with magnetization reversal regions and spin-polarized electron supply regions, where magnetization reversal is induced by currents and magnetic fields parallel to the film surface, allowing for initialization without fixed layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed layers are used for initialization in magnetic domain wall displacement MRAM, then the magnetic domain wall can be properly initialized, but the manufacturing process becomes complicated and the recording layer may be damaged
Solution Approach 1:
The patent extracts and removes the fixed layer component from the MRAM structure. Instead of using fixed layers for initialization, the invention uses a self-initialization mechanism where the recording layer itself is used to initialize the magnetic domain wall through specific current and magnetic field application, eliminating the need for separate fixed layers and simplifying the manufacturing process
Solution Approach 2:
The recording layer serves dual functions: it stores data and also performs the initialization function traditionally performed by fixed layers. By applying current and magnetic field parallel to the film surface, the recording layer initializes its own magnetic domain wall without requiring external fixed layer structures, making the system self-sufficient
2Reliability
If fixed layers are used for initialization, then the magnetic domain wall can be initialized, but leakage magnetic fields increase the write current values
Solution Approach 1:
By removing the fixed layers that generate leakage magnetic fields, the patent eliminates the source of increased write current requirements. The self-initialization mechanism using only the recording layer avoids the harmful leakage fields while maintaining initialization capability
Solution Approach 2:
The patent converts the potential harm of requiring high write currents into a benefit by designing a structure where the recording layer's own magnetic properties and the applied current/magnetic field combination enable initialization without the need for fixed layers, thereby avoiding the leakage field problem entirely
3Reliability
If fixed layers are used in the magnetic domain wall displacement element, then initialization can be achieved, but the structure becomes more complex with additional components
Solution Approach 1:
The patent extracts the initialization function from the fixed layer component and transfers it to the recording layer itself. This removal of the fixed layer simplifies the element structure to essentially one magnetic layer (the recording layer) while maintaining the initialization function through alternative means (current and magnetic field application)
Solution Approach 2:
The recording layer is designed to perform multiple functions: data storage, magnetic domain wall displacement for data writing, and self-initialization. This multi-functionality eliminates the need for separate fixed layers, reducing structural complexity while maintaining all necessary functions
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 simplifies the manufacturing process, reduces the risk of recording layer damage, and lowers write current values, enabling a more reliable and power-efficient magnetic domain wall displacement MRAM.
Implementation Method 1
The reversal phenomenon of magnetization is considered to be caused by either the Rashba field generated by a non-symmetrical three-layer structure formed of a heavy metal layer, a ferromagnetic layer, and an oxidized metal layer
Implementation Method 2
The reversal phenomenon of magnetization is considered to be caused by either the Rashba field generated by a non-symmetrical three-layer structure formed of a heavy metal layer, a ferromagnetic layer, and an oxidized metal layer or the spin-current injection that occurs due to the spin Hall effect of the heavy metal layer
Implementation Method 3
The magnetization reversal is hereinafter referred to as 'current-driven magnetic domain wall displacement'. The magnetic domain wall MW is displaced in the recording layer 10 in accordance with the direction of conduction electrons carrying the write current
Data Source
AI summary
Provided is a magnetic domain wall displacement memory cell, including a recording layer including a magnetic film, the recording layer including: a magnetization reversal region in which magnetization is reversible; and first and second magnetization fixed regions that supply a spin-polarized electron to the magnetization reversal region. The magnetic domain wall displacement memory cell is configured so that a first region in which magnetization reversal occurs due to a first current flowing in a direction parallel to a film surface of the recording layer and a first magnetic field component in the direction parallel to the film surface of the recording layer is formed, and a second region in which no magnetization reversal occurs is formed.