STTMRAM Free Layer Edge Magnetization for Low Voltage Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic random access memory (MRAM) with spin transfer torque magnetic tunnel junctions (MTJs) faces challenges in reducing the threshold voltage and current required to switch the free layer's magnetic state due to inconsistent coercivity across the free layer, limiting the ease of switching and increasing the edge-to-center effective coercivity ratio.
Innovation Solution
A spin transfer torque magnetic random access memory (STTMRAM) element is designed with a reference layer, a junction layer, a free layer, and a fixed layer, where the perpendicular magnetic components of the fixed and reference layers cancel each other, and the free layer has an in-plane magnetization field at its edges, reducing the effective coercivity and allowing easier switching with lower voltage and current requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If perpendicular anisotropy is used in MTJ design to improve density, then storage density is improved, but the edge-to-center effective coercivity ratio increases making switching more difficult
Solution Approach 1:
The patent applies different magnetic field configurations to different regions of the free layer. The in-plane magnetic field is specifically applied at the edges of the free layer to reduce the effective coercivity in those regions, while the center region maintains perpendicular magnetization. This local differentiation allows the edges to switch more easily without compromising the overall perpendicular anisotropy and storage density.
Solution Approach 2:
The patent changes the magnetic field orientation parameter from purely perpendicular to a combination of perpendicular and in-plane fields. By introducing an in-plane magnetic field component at the edges of the free layer, the effective coercivity is reduced, enabling easier switching while maintaining the perpendicular magnetization direction for high-density storage.
2Quantity of substance
If perpendicular magnetization is used in free layer to achieve high density, then storage capacity is improved, but threshold voltage and current requirements increase
Solution Approach 1:
The patent applies different magnetic field configurations to different regions of the free layer. The in-plane magnetic field is specifically applied at the edges of the free layer to reduce the effective coercivity in those regions, while the center region maintains perpendicular magnetization. This local differentiation allows the edges to switch more easily without compromising the overall perpendicular anisotropy and storage density.
Solution Approach 2:
The patent changes the magnetic field orientation parameter from purely perpendicular to a combination of perpendicular and in-plane fields. By introducing an in-plane magnetic field component at the edges of the free layer, the effective coercivity is reduced, enabling easier switching while maintaining the perpendicular magnetization direction for high-density storage.
3Ease of operation
If in-plane magnetization field is applied at edges of free layer to reduce effective coercivity, then switching ease is improved, but magnetic field consistency deteriorates
Solution Approach 1:
The patent applies different magnetic field configurations to different regions of the free layer. The in-plane magnetic field is specifically applied at the edges of the free layer to reduce the effective coercivity in those regions, while the center region maintains perpendicular magnetization. This local differentiation allows the edges to switch more easily without compromising the overall perpendicular anisotropy and storage density.
Solution Approach 2:
The patent segments the magnetic field configuration into different regions: the center of the free layer maintains perpendicular magnetization for stability, while the edges receive in-plane magnetic field assistance for easier switching. This segmentation allows each region to optimize its function without interfering with the other.
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 achieves a significant reduction in switching voltage by approximately 70% compared to conventional MRAM structures, enabling easier and more symmetrical switching of the free layer's magnetic states.
Implementation Method 1
the perpendicular magnetic components of the fixed layer and the reference layer substantially cancel each other
Implementation Method 2
spin torque from electrons transmitted from the pinned layer to the free layer orientates the free layer magnetization in a direction that is parallel to that of the reference or pinned layer
Implementation Method 3
spin torque from electrons that are reflected from the pinned layer back into the free layer orientates the free layer magnetization to be anti-parallel relative to the magnetization of the pinned layer
Data Source
AI summary
A spin transfer torque magnetic random access memory (STTMRAM) element comprises a reference layer, which can be a single layer structure or a synthetic multi-layer structure, formed on a substrate, with a fixed perpendicular magnetic component. A junction layer is formed on top of the reference layer and a free layer is formed on top of the junction layer with a perpendicular magnetic orientation, at substantially its center of the free layer and switchable. A tuning layer is formed on top of the free layer and a fixed layer is formed on top of the tuning layer, the fixed layer has a fixed perpendicular magnetic component opposite to that of the reference layer. The magnetic orientation of the free layer switches relative to that of the reference layer. The perpendicular magnetic components of the fixed layer and the reference layer substantially cancel each other and the free layer has an in-plane edge magnetization field.