MRAM Spin Barrier Layer for Magnetization Reversal
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Solution Overview
Problem
In magnetic random access memories (MRAMs), the miniaturization of elements leads to difficulties in passing sufficient currents for magnetization reversal, and the spin pumping phenomenon increases the current required for magnetization reversal, reducing spin injection efficiency and thermal stability.
Innovation Solution
A storage element configuration with a spin barrier layer, composed of oxides, nitrides, or fluorides, is introduced on the side opposite to the pinned magnetization layer to restrain spin diffusion, reducing the current needed for magnetization reversal and enhancing thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If element size is miniaturized to increase storage density, then storage capacity is improved, but current required for magnetization reversal increases due to spin pumping phenomenon
Solution Approach 1:
A nonmagnetic metal layer is introduced as an intermediary between the storage layer and the underlying structure. This layer acts as a spin sink that absorbs spin-polarized electrons, preventing them from pumping back into the storage layer and causing magnetization reversal. This mediator approach reduces the harmful spin pumping effect while maintaining efficient spin injection for magnetization switching.
Solution Approach 2:
The patent modifies the structural parameters of the storage element by adding the nonmagnetic metal layer and optimizing its thickness. This parameter change alters the spin transport properties, reducing spin diffusion length and minimizing the spin pumping phenomenon, thereby lowering the current required for magnetization reversal in miniaturized elements.
2Reliability
If current is increased to overcome spin pumping effect, then magnetization reversal is achieved, but spin injection efficiency decreases
Solution Approach 1:
The nonmagnetic metal layer serves as a spin sink that intercepts spin-polarized electrons before they can pump back into the storage layer. This intermediary structure prevents energy loss through spin pumping while maintaining reliable magnetization reversal, thereby improving spin injection efficiency without sacrificing reversal reliability.
3Reliability
If current for magnetization reversal is increased, then stable writing is achieved, but thermal stability of storage layer deteriorates
Solution Approach 1:
The nonmagnetic metal layer acts as a spin sink that reduces the current required for magnetization reversal by preventing spin pumping. This lower operating current reduces Joule heating and thermal effects on the storage layer, thereby maintaining writing stability while preserving or improving the thermal stability of the stored information.
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 reduces the current required for magnetization reversal, improves spin injection efficiency, and enhances thermal stability, enabling stable information storage with lower power consumption and increased operation margin.
Implementation Method 1
a storage layer for storing a magnetization state of a ferromagnetic layer as information
Implementation Method 2
the direction of magnetization of the storage layer is changed through injection of spin polarized electrons therein by passing a current in a direction perpendicular to the film plane
Implementation Method 3
reading of the information is achieved by use of the so-called magnetoresistance effect (MR effect) in which resistance varies according to the direction of magnetization of the storage layer
Data Source
AI summary
A storage element including a storage layer configured to hold information by use of a magnetization state of a magnetic material, with a pinned magnetization layer being provided on one side of the storage layer, with a tunnel insulation layer, and with the direction of magnetization of the storage layer being changed through injection of spin polarized electrons by passing a current in the lamination direction, so as to record information in the storage layer, wherein a spin barrier layer configured to restrain diffusion of the spin polarized electrons is provided on the side, opposite to the pinned magnetization layer, of the storage layer; and the spin barrier layer includes at least one material selected from the group composing of oxides, nitrides, and fluorides.