Magnetic Tunneling Junction Structure for Field-Free MRAM Switching
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Solution Overview
Problem
Magnetic memory devices, such as MRAM, require an external magnetic field for selective magnetic switching, which complicates their structure and operation.
Innovation Solution
A magnetic tunneling junction device with a synthetic antiferromagnet, a free layer, a separation metal layer, and a pinned layer, where the first and second ferromagnetic layers have opposite magnetization directions aligned to the current, allowing for magnetic switching without an external magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external magnetic field is applied for selective magnetic switching, then magnetic switching can be achieved, but the structure and operation become complicated
Solution Approach 1:
The invention extracts and eliminates the external magnetic field component from the magnetic switching mechanism. By using a synthetic antiferromagnet structure with coupled ferromagnetic layers, the magnetic switching is achieved through internal spin interactions rather than external field application, thereby simplifying the device structure while maintaining reliable magnetic switching capability
Solution Approach 2:
The synthetic antiferromagnet acts as an intermediary structure that mediates between the pinned layer and free layer. The coupled ferromagnetic layers with opposite magnetization directions create spin interactions that enable selective magnetic switching without requiring external magnetic field, thus resolving the contradiction between switching reliability and structural complexity
2Device complexity
If a synthetic antiferromagnet structure is used for magnetic switching without external magnetic field, then device complexity is reduced, but magnetic switching capability must be maintained
Solution Approach 1:
The invention employs a composite synthetic antiferromagnet structure consisting of multiple ferromagnetic layers coupled through a nonmagnetic metal layer. This composite structure enables magnetic switching without external field by utilizing the spin interactions between layers with opposite magnetization directions, maintaining switching reliability while reducing device complexity
Solution Approach 2:
The invention changes the magnetization direction parameters of the ferromagnetic layers to be opposite to each other in the synthetic antiferromagnet structure. This parameter configuration enables the system to achieve magnetic switching through internal spin torques rather than external fields, maintaining switching capability while simplifying the overall device structure
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 high-speed operation and stable magnetic switching of the free layer without an external magnetic field, reducing the complexity of the memory device structure and improving operational efficiency.
Implementation Method 1
spin-orbit torque (SOT)-MRAM may have a very fast operation speed less than or equal to 5 nsec
Implementation Method 2
spin transfer torque-magnetic RAM (STT-MRAM) that is currently mass-produced
Implementation Method 3
The resistance of the magnetic tunneling junction device varies with the magnetization direction of a free layer
Data Source
AI summary
A magnetic tunneling junction device includes a synthetic antiferromagnet, a separation metal layer disposed on the synthetic antiferromagnet, a free layer disposed on the separation metal layer and having a variable magnetization direction, an oxide layer disposed on the free layer, and a pinned layer disposed on the oxide layer and having a pinned magnetization direction. The synthetic antiferromagnet may include a first ferromagnetic layer, a non-magnetic metal layer disposed on the first ferromagnetic layer, and a second ferromagnetic layer disposed on the non-magnetic metal layer. Magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer may be opposite to each other in an in-plane direction and aligned to be inclined with respect to a direction of a current applied to the synthetic antiferromagnet.