Magnetic Memory Element With Segmented Free Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current magnetic random access memory (MRAM) technologies face challenges in reducing writing current while maintaining thermal stability and scalability, particularly when using current-induced domain wall motion with materials having perpendicular magnetic anisotropy, as the initialization margin is limited by the magnetic properties of the fixed layers.
Innovation Solution
A magnetic memory element with a first magnetization free layer, a non-magnetic layer, a reference layer, and a first magnetization fixed layer group, where the first magnetization free layer includes regions with anti-parallel magnetization and a blocking layer to control the magnetic coupling, allowing for a larger initialization margin and easier fabrication by applying external magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If current-induced domain wall motion is used with materials having perpendicular magnetic anisotropy, then writing speed is improved, but initialization margin is limited by magnetic properties of fixed layers
Solution Approach 1:
The magnetization free layer is divided into multiple regions with different magnetization directions (first region with upward magnetization, second region with downward magnetization, and third region with switchable magnetization). This segmentation allows independent control of initialization and data storage functions, enabling larger initialization margin while maintaining fast writing speed through domain wall motion.
Solution Approach 2:
A non-magnetic layer is introduced as an intermediary between the magnetization free layer and the reference layer. This intermediary layer decouples the magnetic interaction, allowing the fixed layers to provide strong pinning for thermal stability without constraining the initialization margin, thus enabling both fast writing and easy initialization.
2Speed
If magnetic field switching is used to switch magnetization direction, then writing speed is improved, but writing current increases to several mA
Solution Approach 1:
The patent replaces the conventional magnetic field switching mechanism (which requires high current through wiring lines) with current-induced domain wall motion. The writing current flows directly through the magnetization free layer to generate spin transfer torque, which drives domain wall motion and switches magnetization direction. This substitution eliminates the need for peripheral wiring lines and reduces writing current to sub-mA levels while maintaining nanosecond-speed writing.
3Productivity
If spin transfer magnetization switching is used, then scaling performance is improved, but writing current flows through insulating film causing reliability issues
Solution Approach 1:
The magnetic memory element is segmented into distinct functional regions: the reference layer for reading, the non-magnetic layer for isolation, and the magnetization free layer with multiple regions for writing and storage. This segmentation separates the writing current path (through the magnetization free layer) from the reading current path (through the reference layer and non-magnetic layer), allowing spin transfer switching to scale while avoiding reliability issues by preventing current flow through insulating films during writing operations.
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 proposed structure and initializing method enable a larger initialization margin and easier manufacturing of MRAM with current-induced domain wall motion, improving the scalability and efficiency of data writing in MRAM while reducing the writing current.
Implementation Method 1
a first magnetization free layer composed of ferromagnetic material with perpendicular magnetic anisotropy
Implementation Method 2
applying a first magnetic field to the magnetic memory element in a direction approximately perpendicular to an upper surface of a first magnetization free layer; and applying a second magnetic field whose absolute value is smaller than that of the first magnetic field to the magnetic memory element in a direction opposite to that of the first magnetic field
Implementation Method 3
a first blocking layer provided being sandwiched between the first magnetization fixed layer group and the first magnetization fixed region or in the first magnetization fixed layer group
Data Source
AI summary
A magnetic memory element includes: a first magnetization free layer; a non-magnetic layer; a reference layer; a first magnetization fixed layer group; and a first blocking layer. The first magnetization free layer is composed of ferromagnetic material with perpendicular magnetic anisotropy and includes a first magnetization fixed region, a second magnetization fixed region and a magnetization free region. The non-magnetic layer is provided near the first magnetization free layer. The reference layer is composed of ferromagnetic material and provided on the non-magnetic layer. The first magnetization fixed layer group is provided near the first magnetization fixed region. The first blocking layer is provided being sandwiched between the first magnetization fixed layer group and the first magnetization fixed region or in the first magnetization fixed layer group.