Magnetic Tunneling Junction with Easy Cone Anisotropy
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Solution Overview
Problem
Conventional spin transfer torque random access memories (STT-RAMs) face high write error rates and scalability issues due to the limitations of existing magnetic tunnel junction (MTJ) structures, particularly in achieving low critical switching currents and high data rates with short write current pulses.
Innovation Solution
The introduction of a magnetic junction with a pinned layer, a nonmagnetic spacer layer, and a free layer exhibiting easy cone magnetic anisotropy, allowing the free layer to switch between stable magnetic states with improved write error rates and thermal stability, even at low pulse widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional magnetic tunnel junction structures are used in STT-RAM, then the device can store information using magnetic materials, but high write error rates and scalability issues occur due to limitations in achieving low critical switching currents
Solution Approach 1:
The magnetic junction is segmented into multiple functional layers including a pinned layer with perpendicular magnetic anisotropy, a nonmagnetic spacer layer, and a free layer with easy cone anisotropy. This segmentation allows independent optimization of each layer's magnetic properties to achieve low critical switching current while maintaining thermal stability, thereby reducing write error rates without excessive complexity
Solution Approach 2:
The invention employs composite magnetic layer structures where the pinned layer and free layer have different magnetic anisotropy characteristics (perpendicular vs. easy cone). This composite structure enables the system to achieve both low switching current and high thermal stability by combining materials with complementary magnetic properties, improving reliability while managing device complexity
2Productivity
If conventional magnetic junction structures are used, then information can be stored magnetically, but scalability issues arise due to inability to achieve high data rates with short write current pulses
Solution Approach 1:
The invention changes the magnetic anisotropy parameters of the free layer to exhibit easy cone anisotropy instead of conventional in-plane or perpendicular anisotropy. This parameter change enables the free layer to respond more rapidly to spin transfer torque, achieving high data rates with short write current pulses and improving productivity while reducing the duration requirement
Solution Approach 2:
The easy cone anisotropy configuration creates a dynamic magnetic response where the magnetization can quickly switch between stable states when subjected to spin polarized current. This dynamic behavior enables high-speed switching operations, achieving scalability for high data rate applications with reduced pulse width requirements
3Stability of the object's composition
If the free layer uses conventional magnetic anisotropy, then switching can be achieved, but thermal stability is compromised at low pulse widths
Solution Approach 1:
The invention applies different magnetic anisotropy qualities to different layers: the pinned layer has perpendicular magnetic anisotropy for stability, while the free layer has easy cone anisotropy for rapid switching. This local differentiation allows the free layer to maintain thermal stability even at low pulse widths while enabling fast switching, resolving the contradiction between stability and pulse duration
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 enhances the switching characteristics and scalability of magnetic memories by reducing write error rates and maintaining thermal stability, enabling acceptable performance at high data rates without the need for external magnetic fields.
Implementation Method 1
A spin polarized current driven through the magnetic junction exerts a spin torque on the magnetic moments in the magnetic junction. As a result, layer(s) having magnetic moments that are responsive to the spin torque may be switched to a desired state.
Implementation Method 2
The free layer has an easy cone magnetic anisotropy. The magnetic junction is configured such that the free layer is switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction.
Implementation Method 3
a nonmagnetic layer formed between the first magnetic layer and the second magnetic layer
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A method and system for providing a magnetic junction usable in a magnetic device are described. The magnetic junction includes a pinned layer (110), a nonmagnetic spacer layer (120), and a free layer (130). The nonmagnetic spacer layer (120) is between the pinned layer (110) and the free layer (130). The free layer (130) has an easy cone magnetic anisotropy. The magnetic junction is configured such that the free layer (130) is switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction.