Self-Referenced MRAM Cell Using Spin-Orbit Torque
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Solution Overview
Problem
The scalability of self-reference magnetic random access memory (MRAM) cells is limited by the field lines required for reading and writing, which restricts the miniaturization of memory devices.
Innovation Solution
The use of a self-referenced MRAM cell design that employs a magnetic tunnel junction with a storage layer, a tunnel barrier layer, and a sense layer connected via a seed layer with high spin-orbit coupling, allowing for switching of the sense magnetization using spin-orbit torque without the need for field lines, enabling reduced size and efficient read/write operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If field lines are used for reading and writing operations, then magnetization switching can be achieved, but the memory device size increases and scalability is reduced
Solution Approach 1:
The patent extracts and eliminates the field line structure from the MRAM cell design. By removing the field lines and replacing them with spin-orbit torque switching mechanisms, the invention reduces the memory device area while maintaining magnetization switching capability through a different physical mechanism (spin Hall effect and Rashba effect instead of magnetic field coupling).
Solution Approach 2:
The patent substitutes the magnetic field-based switching mechanism (mechanical/electromagnetic system) with an electric current-based spin-orbit torque mechanism. This replacement eliminates the need for field lines and associated wiring, thereby reducing device area and improving scalability while preserving the essential function of magnetization switching.
2Ease of operation
If field lines are used for read operations, then sense magnetization can be switched, but the device complexity and size increase
Solution Approach 1:
The patent removes the field line infrastructure from the read operation mechanism. By extracting this component, the invention simplifies the device structure and reduces complexity while maintaining the ability to switch sense magnetization through spin-orbit torque applied via current flow in the seed layer.
3Ease of operation
If conventional spin transfer torque is used, then magnetization switching is achieved, but a polarizing layer is required increasing device size
Solution Approach 1:
The patent extracts and eliminates the polarizing layer from the spin transfer torque mechanism. By replacing conventional STT with spin-orbit torque (SOT) switching, the invention removes the need for spin-polarized current and associated polarizing layers, reducing device area while maintaining magnetization switching functionality through spin Hall effect and Rashba effect mechanisms.
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 eliminates the need for field lines during read and write operations, allowing for reduced size and improved scalability of MRAM cells and memory devices, while maintaining efficient magnetization switching through spin-orbit torque, which combines the advantages of spin transfer torque without requiring a polarizing layer.
Implementation Method 1
passing a sense current along the plane of the sense layer and/or seed layer exerts a spin-orbit torque adapted for switching the sense magnetization
Data Source
AI summary
A self-referenced MRAM cell comprises a first portion of a magnetic tunnel junction including a storage layer; a second portion of the magnetic tunnel junction portion including a tunnel barrier layer, a sense layer and a seed layer; the seed layer comprising a material having high spin-orbit coupling such that passing a sense current along the plane of the sense layer and/or seed layer exerts a spin-orbit torque adapted for switching a sense magnetization of the sense layer. A memory device comprising a plurality of the MRAM cells and a method for operating the memory device are also disclosed.