Spin Hall Effect MRAM Self-Reference Read Architecture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Spin torque MRAM devices require high current for writing, and existing solutions using the spin hall effect increase cell area due to the need for three terminals, making them impractical for some applications.
Innovation Solution
The use of two spin hall wires, one above and one below the tunnel junction, allows for writing the storage layer with reduced current requirements and enables a self-reference read mechanism by using the second spin hall wire to write the sense layer during reading, thereby simplifying the read process and reducing cell area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If spin torque MRAM uses conventional writing method, then writing function is achieved, but high current is required
Solution Approach 1:
The patent replaces the conventional spin transfer torque (STT) mechanism with the spin hall effect (SHE) mechanism. Instead of using spin-polarized current directly through the magnetic tunnel junction to switch magnetization, the invention uses a spin hall wire adjacent to the junction that generates spin current via the spin hall effect when charge current flows through it. This substitution reduces the writing current requirement while maintaining switching reliability.
2Use of energy by moving object
If three-terminal spin hall effect structure is used, then writing current is reduced, but cell area increases
Solution Approach 1:
The patent merges the read and write functions into a two-terminal structure by integrating the spin hall wire directly with the magnetic tunnel junction. The same two terminals used for reading also enable writing through the spin hall effect, eliminating the need for separate write terminals. This merging reduces the cell area while maintaining the low writing current advantage of the spin hall effect.
Solution Approach 2:
The two-terminal structure serves multiple functions: it enables both reading (through tunneling current measurement) and writing (through spin hall effect current application) operations. The spin hall wire and magnetic tunnel junction together form a multi-functional component that performs both memory read and write operations, reducing the overall device complexity and area.
3Measurement precision
If self-reference read is implemented, then read accuracy is improved, but additional writing operation is required
Solution Approach 1:
The patent implements a self-reference read mechanism where the sense layer's own magnetization state serves as the reference for reading the storage layer. By writing the sense layer to a known state and then measuring the change in tunneling current, the system uses itself as the reference, eliminating the need for external reference structures. This self-service approach improves read accuracy while minimizing additional time overhead.
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 reduces the current needed for writing and allows for efficient self-reference reading without disturbing the stored data, improving the practicality and efficiency of spin torque MRAM devices.
Implementation Method 1
Proposed solutions have involved using the spin hall effect to generate spin current. With the spin hall effect, the spin current is generated in a transverse direction while a charge current flows in a longitudinal direction.
Data Source
AI summary
Techniques for writing magnetic random access memory (MRAM) using the spin hall effect with a self-reference read are provided. In one aspect, an MRAM device is provided. The MRAM device includes: a plurality of first spin hall wires oriented orthogonal to a plurality of second spin hall wires; a plurality of magnetic memory cells configured in an array between the first spin hall wires and the second spin hall wires; and a plurality of transistors connected to the magnetic memory cells by the first spin hall wires. Methods of operating an MRAM device are also provided.