Spin-orbit torque magnetic memory cell design
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Solution Overview
Problem
Current memory technologies face challenges in achieving low power consumption, high speed, and dense scalability while efficiently storing and retrieving magnetic information.
Innovation Solution
A nonvolatile memory cell design that utilizes a fixed magnetic layer, a nonmagnetic electrode, a memory storage layer with magnetic material, and a tunnel barrier layer, where electrical current switches magnetization to store and retrieve memory bits using magnetic spin rotation and the magnetic spin Hall effect, allowing for high endurance and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional memory technologies are used, then storage capacity and speed can be achieved, but power consumption increases and scalability is limited
Solution Approach 1:
The patent replaces conventional charge-based memory mechanisms with spin-based magnetic mechanisms. Electrical current flows through a nonmagnetic electrode to generate spin-orbit torque, which switches the magnetization state of the memory storage layer. This mechanical-to-magnetic substitution enables nonvolatile storage with lower power consumption during read/write operations, as no continuous power is needed to maintain the stored state.
Solution Approach 2:
The memory cell employs a composite multilayer structure including a magnetic storage layer with perpendicular magnetic anisotropy, a nonmagnetic electrode with high spin-orbit coupling, and a tunnel barrier layer. This composite structure combines materials with complementary properties: the magnetic layer provides stable binary states, the nonmagnetic electrode generates efficient spin torque, and the tunnel barrier enables magnetoresistive readout, achieving both low power consumption and high storage density.
2Quantity of substance
If storage density is increased, then more memory bits can be stored, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent utilizes perpendicular magnetization orientation, switching the magnetic moments from in-plane to out-of-plane direction. This dimensional change enables higher storage density by allowing smaller cell footprints while maintaining stable magnetic states. The perpendicular magnetic anisotropy in the storage layer enables binary states to be represented by upward or downward magnetization directions, facilitating dense three-dimensional stacking and scaling without proportionally increasing device complexity.
3Speed
If write speed is increased to achieve high performance, then data retrieval is faster, but power consumption and energy loss increase
Solution Approach 1:
The patent changes the switching mechanism parameter from charge-based to spin-based, utilizing spin-orbit torque generated in a nonmagnetic electrode with high spin Hall angle or Rashba effect. By adjusting material composition and thickness parameters of the magnetic storage layer to achieve perpendicular magnetic anisotropy, the switching energy barrier is optimized. This enables fast magnetization reversal at lower current densities, achieving high write speed with reduced energy loss compared to conventional spin-transfer torque or voltage-controlled magnetic anisotropy methods.
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
The solution provides low power consumption, high speed, and extremely dense scalability, enabling efficient storage and retrieval of memory bits with high endurance and density.
Implementation Method 1
electrical current flowing in a first direction through the first nonmagnetic electrode switches magnetization in the memory storage layer that includes magnetic material to store the memory bit
Implementation Method 2
magnetic spin rotation in combination with a magnetic spin Hall effect provide memory bit storage and retrieval
Implementation Method 3
a first fixed magnetic layer comprising a first fixed magnetic state and that conducts electrical current; a first nonmagnetic electrode disposed on the first magnetic layer and that conducts electrical current
Implementation Method 4
a tunnel barrier layer disposed on the memory storage layer such that the memory storage layer is interposed between the tunnel barrier layer and the first nonmagnetic electrode
Data Source
AI summary
A nonvolatile memory cell includes: a first fixed magnetic layer; a first nonmagnetic electrode disposed on the first magnetic layer; a memory storage layer disposed on the first nonmagnetic electrode; a tunnel barrier layer disposed on the memory storage layer; a second fixed magnetic layer disposed on the tunnel barrier layer; and a second nonmagnetic electrode disposed on the second fixed magnetic layer.