SOT-MRAM Cell Using Orbital Hall Effect for Field-Free Writing
Solution Overview
Problem
SOT-MRAM with perpendicular magnetic anisotropy requires external in-plane magnetic fields for data writing, limiting integration and miniaturization, and relies on expensive heavy metal materials for spin-orbit coupling, which hinders cost reduction and compatibility with CMOS processes.
Innovation Solution
The SOT-MRAM memory cell employs an orbital Hall effect layer and a spin-orbit coupling layer to convert write currents into orbital-polarized and spin-polarized currents, forming a competition spin current for deterministic magnetization reversal without external magnetic fields, using materials compatible with CMOS processes and reducing heavy metal usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external in-plane magnetic field assistance is used for data writing in SOT-MRAM with perpendicular magnetic anisotropy, then data writing can be achieved, but integration and miniaturization are limited
Solution Approach 1:
The patent extracts and eliminates the external magnetic field component from the writing mechanism, achieving field-free magnetization reversal through pure spin-orbit torque. By removing the external magnetic field requirement, the device structure is simplified and integration density can be improved without compromising writing capability
Solution Approach 2:
The patent changes the fundamental parameter of magnetization reversal from field-assisted to field-free by utilizing spin-orbit coupling effects. This parameter change enables deterministic switching without external magnetic fields, resolving the contradiction between reliable writing and device integration
2Reliability
If expensive heavy metal materials are used as spin-orbit coupling layers, then spin-orbit coupling effect is achieved, but cost reduction is hindered
Solution Approach 1:
The patent replaces expensive heavy metal materials with cheaper alternative materials that can still provide the necessary spin-orbit coupling effect. This substitution maintains the functional reliability while significantly reducing manufacturing cost, making large-scale production more feasible
Solution Approach 2:
The patent employs composite material structures that combine different materials to achieve the spin-orbit coupling effect more cost-effectively. By using composite approaches rather than pure heavy metals, the device maintains performance while reducing material cost
3Reliability
If heavy metal materials are used for spin-orbit coupling, then spin current generation is achieved, but compatibility with CMOS processes is poor
Solution Approach 1:
The patent substitutes heavy metal materials with materials that are compatible with standard CMOS fabrication processes. This replacement maintains spin current generation capability while enabling integration with existing CMOS manufacturing infrastructure, improving overall ease of manufacture
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 enables full electrical control of magnetization reversal without external magnetic fields, simplifies the device structure, reduces expensive heavy metal usage, and enhances compatibility with CMOS processes, facilitating large-scale integration and practicality of SOT-MRAM.
Implementation Method 1
The orbital Hall effect layer is configured to convert the write current into an orbital-polarized orbital current through an orbital Hall effect
Implementation Method 2
The heavy metal layer is configured to convert the write current into a spin-polarized spin current through a spin-orbit coupling
Implementation Method 3
The orbital current that diffuses into the heavy metal layer is converted into a spin current under a strong spin-orbit coupling effect of the heavy metal layer
Implementation Method 4
The competition spin current is configured to achieve a deterministic magnetization reversal without external magnetic field assistance
Data Source
AI summary
The present disclosure provides an SOT-MRAM memory cell, including: a bottom electrode; a magnetic tunnel junction layer located on the bottom electrode; an orbital Hall effect layer located on the magnetic tunnel junction layer; a first transistor, a drain of which is connected to the orbital Hall effect layer; and a second transistor, a drain of which is connected to the bottom electrode. The present disclosure further provides an SOT-MRAM memory, an operation method, and an SOT-MRAM memory array.