Magnetic Memory Device Stacked Oxide Tunnel Barrier VCMA Write Current
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Solution Overview
Problem
Conventional magnetoresistive elements do not sufficiently reduce write current, which is essential for efficient operation in magnetic memory devices.
Innovation Solution
A magnetic memory device with a stacked structure incorporating a storage layer, a reference layer, a tunnel barrier layer, and a shift canceling layer, where the tunnel barrier layer is formed by stacking a first oxide layer with a lower relative dielectric constant and a second oxide layer with a higher relative dielectric constant, utilizing the voltage-control of magnetic anisotropy (VCMA) effect to reduce write current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional magnetoresistive elements are used, then the device structure is simple, but the write current cannot be sufficiently reduced
Solution Approach 1:
The tunnel barrier layer is segmented into a stacked structure comprising a first oxide layer and a second oxide layer with different relative dielectric constants. This segmentation allows the VCMA effect to be selectively enhanced through the high dielectric constant second oxide layer, reducing write current while maintaining TMR ratio.
Solution Approach 2:
The tunnel barrier layer uses a composite structure of two different oxide materials with distinct dielectric properties. The first oxide layer provides baseline tunneling characteristics, while the second oxide layer with higher relative dielectric constant enhances the VCMA effect, achieving reduced write current without sacrificing TMR performance.
2Use of energy by moving object
If the tunnel barrier layer uses a single oxide material, then the manufacturing process is simple, but the VCMA effect is insufficient to reduce write current
Solution Approach 1:
The tunnel barrier layer is divided into two distinct oxide layers that can be fabricated using standard sequential deposition processes. Each layer can be independently controlled for thickness and composition, allowing optimization of the VCMA effect while using established manufacturing techniques.
Solution Approach 2:
The invention changes the dielectric parameter (relative dielectric constant) by selecting different oxide materials for the two layers. This parameter change enhances the VCMA effect in the second layer, enabling write current reduction while maintaining compatibility with existing fabrication processes.
3Use of energy by moving object
If write current is reduced using VCMA effect, then energy efficiency improves, but the energy barrier for magnetization reversal must be precisely controlled
Solution Approach 1:
The second oxide layer with higher relative dielectric constant is strategically positioned adjacent to the storage layer where the VCMA effect is most needed. This local quality enhancement concentrates the electric field effect where it most effectively reduces the energy barrier for magnetization reversal, optimizing write current reduction.
Solution Approach 2:
By adjusting the thickness and dielectric constant parameters of the two oxide layers, the overall energy barrier for magnetization reversal can be precisely controlled. The stacked structure provides independent parameter optimization for each layer, enabling fine-tuning of the VCMA effect to achieve desired write current levels.
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 VCMA effect decreases the energy barrier for magnetization reversal, allowing for reduced write current while maintaining a high Tunnel Magnetoresistance (TMR) ratio, enabling efficient data storage in magnetic memory devices.
Implementation Method 1
utilizing the voltage-control of magnetic anisotropy (VCMA) effect to reduce write current
Implementation Method 2
the nonmagnetic layer comprises a structure in which a first oxide layer formed of a first metal oxide and a second oxide layer formed of a second metal oxide having a relative dielectric constant greater than a relative dielectric constant of the first metal oxide are stacked
Implementation Method 3
maintaining a high Tunnel Magnetoresistance (TMR) ratio
Data Source
AI summary
According to one embodiment, a magnetic memory device includes a stacked structure, the stacked structure including a first magnetic layer having a variable magnetization direction, a second magnetic layer having a fixed magnetization direction and a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer, wherein the nonmagnetic layer comprises a structure in which a first oxide layer formed of a first metal oxide and a second oxide layer formed of a second metal oxide having a relative dielectric constant greater than a relative dielectric constant of the first metal oxide are stacked.