Perpendicular Magnetoresistive Element with Oscillation Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-density nonvolatile magnetic random access memories (MRAMs) face challenges in maintaining magnetic anisotropy and thermal disturbance resistance as element size decreases, requiring improved magnetization control and reduced writing current for efficient data storage.
Innovation Solution
A magnetoresistive element with a perpendicular-magnetization structure, incorporating a magnetization oscillation layer generating rotating magnetic fields of different frequencies to assist magnetization switching, reducing the write current and enhancing thermal stability through a granular film structure or stacked ferromagnetic layers with nonmagnetic interlayers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If element size is decreased to achieve high-density integration, then storage density is improved, but thermal disturbance resistance and magnetic anisotropy are degraded
Solution Approach 1:
The patent changes the magnetization orientation parameter from in-plane to perpendicular magnetization, and adjusts the composition ratio of ferromagnetic materials (e.g., CoFeB with specific boron content) to achieve high magnetic anisotropy energy density. This allows maintaining thermal stability even at reduced element sizes for high-density integration
Solution Approach 2:
The patent uses composite ferromagnetic materials such as CoFeB alloys combined with specific thickness ratios of magnetic layers and nonmagnetic layers. The composite structure of multiple ferromagnetic layers with perpendicular magnetization provides enhanced thermal disturbance resistance while enabling high-density storage
2Ease of manufacture
If conventional in-plane magnetization MTJ elements are used, then manufacturing is simpler, but write current is excessively high and thermal stability is insufficient
Solution Approach 1:
The patent transitions from in-plane magnetization to perpendicular magnetization, changing the dimension of magnetization orientation. This dimensional change enables much lower write currents (by an order of magnitude) while improving thermal stability, despite increased manufacturing complexity
Solution Approach 2:
The patent changes material composition parameters (e.g., CoFeB with 0.5-2.0 at% boron) and layer thickness parameters to optimize perpendicular magnetic anisotropy, achieving low write current operation while maintaining manufacturing feasibility through sputtering processes
3Reliability
If perpendicular-magnetization MTJ elements are manufactured to improve thermal stability, then thermal disturbance resistance is improved, but write current reduction is limited without additional structures
Solution Approach 1:
The patent introduces a magnetization oscillation layer that generates spin waves (magnetic vibrations) at specific frequencies. These oscillations assist the spin-polarized current in switching magnetization, significantly reducing the required write current while maintaining thermal stability of perpendicular-magnetization structures
Solution Approach 2:
The magnetization oscillation layer acts as an intermediary that mediates between the spin-polarized current and the storage layer magnetization. It converts electrical current into magnetic oscillations that facilitate lower-energy magnetization switching in perpendicular-magnetization MTJ elements
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 wider write current ranges, reduced write current, and stable high-efficiency spin-injection writing, maintaining thermal stability and magnetic anisotropy even with varying resonant frequencies, enabling high-density, low-power MRAMs.
Implementation Method 1
Spin-polarized electrons are injected into the first ferromagnetic layer and induce precession movements in the plurality of ferromagnetic oscillators of the third ferromagnetic layer
Implementation Method 2
The rotating magnetic fields are generated by the precession movements and are applied to the first ferromagnetic layer
Implementation Method 3
A MRAM characteristically stores information ('1', '0') depending on changes in the relative angle of the magnetizations of magnetic layers included in each MTJ element
Data Source
AI summary
A magnetoresistive element according to an embodiment includes: a first to third ferromagnetic layers, and a first nonmagnetic layer, the first and second ferromagnetic layers each having an axis of easy magnetization in a direction perpendicular to a film plane, the third ferromagnetic layer including a plurality of ferromagnetic oscillators generating rotating magnetic fields of different oscillation frequencies from one another. Spin-polarized electrons are injected into the first ferromagnetic layer and induce precession movements in the plurality of ferromagnetic oscillators of the third ferromagnetic layer by flowing a current between the first and third ferromagnetic layers, the rotating magnetic fields are generated by the precession movements and are applied to the first ferromagnetic layer, and at least one of the rotating magnetic fields assists a magnetization switching in the first ferromagnetic layer.