Spin Memory With Perpendicular Magnetization For Low Current Writing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional magneto-resistance elements require high current densities for spin injection writing, leading to potential destruction of tunnel barriers and large-sized peripheral circuits, and high power consumption, making it difficult to achieve stable and efficient writing in MRAMs.
Innovation Solution
A spin memory and spin FET design that includes a magneto-resistance element with a magnetic pinned layer, a magnetic free layer, and a nonmagnetic layer, where spin-polarized electrons are supplied to the magnetic free layer and a magnetic field is applied from electrodes at an angle between 45 degrees and 90 degrees relative to the hard magnetization axis, reducing the write current and preventing leak magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spin injection writing is performed using conventional TMR elements, then magnetization inversion can be achieved, but the current density required is as high as 8×10^6 A/cm^2, leading to destruction of tunnel barrier and large-sized peripheral circuits
Solution Approach 1:
The patent changes the orientation parameter of the magnetic free layer, making it perpendicular to the film plane instead of in-plane. This parameter change enables spin injection writing with much lower current density (one order of magnitude reduction) while maintaining writing stability and avoiding tunnel barrier destruction
Solution Approach 2:
The patent employs a composite magnetic layer structure consisting of a magnetic pinned layer, nonmagnetic layer, and magnetic free layer with perpendicular magnetization. This composite structure with specific material combinations enables efficient spin transfer torque while reducing the required write current density
2Ease of operation
If high current density is applied for spin injection writing, then magnetization inversion is achieved, but tunnel barrier destruction and peripheral circuit damage occur
Solution Approach 1:
By changing the magnetization orientation parameter of the magnetic free layer to perpendicular orientation, the patent achieves writing capability with low current density, eliminating the harmful effect of tunnel barrier destruction that occurs with high current density conventional methods
3Productivity
If magnetic field write system is used, then writing can be performed, but power consumption is large and current density of wires is limited, making it impossible to achieve large capacity
Solution Approach 1:
The patent replaces the magnetic field-based writing mechanism with a spin transfer torque-based mechanism. This substitution eliminates the need for high current pulses through wires, reducing power consumption and enabling large capacity MRAM implementation while maintaining fast writing speed
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 configuration allows for stable spin injection magnetization inversion with reduced write current, minimizing the risk of tunnel barrier destruction and peripheral circuit issues, while also decreasing power consumption and erroneous writing.
Implementation Method 1
writing is carried out by supplying spin-polarized electrons to the second ferromagnetic layer
Implementation Method 2
magnetization of a magnetic free layer is inversed by injecting a spin-polarized current into the magnetic free layer of a memory element
Implementation Method 3
applying a magnetic field from the lower electrode and the upper electrode to the second ferromagnetic layer
Implementation Method 4
a magneto-resistance element having a first ferromagnetic layer in which a magnetization direction is pinned, a second ferromagnetic layer in which a magnetization direction changes
Data Source
AI summary
A spin memory includes a magneto-resistance element having a first ferromagnetic layer in which a magnetization direction is pinned, a second ferromagnetic layer in which a magnetization direction changes, and a first nonmagnetic layer between the first and second ferromagnetic layers, a lower electrode and an upper electrode extending in a direction between 45 degrees and 90 degrees relative to an axis of hard magnetization of the second ferromagnetic layer, and sandwiching the magneto-resistance element at one end in a longitudinal direction, a switching element connected to another end in a longitudinal direction of the lower electrode, and a bit line connected to another end in a longitudinal direction of the upper electrode, wherein writing is carried out by supplying spin-polarized electrons to the second ferromagnetic layer and applying a magnetic field from the lower electrode and the upper electrode to the second ferromagnetic layer.