Ferromagnetic Layer Boron Gradient for Write Error Rate
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Solution Overview
Problem
Magnetic memory devices face challenges in optimizing the magnetization properties and retention characteristics of magnetoresistive effect elements, particularly in achieving low saturation magnetization while maintaining high retention properties and reducing write error rates.
Innovation Solution
A magnetic memory device configuration with a layer stack including a first and second ferromagnetic layer, separated by nonmagnetic layers with varying boron content, and utilizing magnesium oxide to promote crystallization and interface flatness, allowing for controlled magnetization and improved anisotropic magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the saturation magnetization of the ferromagnetic layer is reduced to improve write error rate, then the retention properties deteriorate
Solution Approach 1:
The patent applies local quality by creating a non-uniform boron concentration distribution within the ferromagnetic layer. The boron concentration is higher at the interface with the first nonmagnetic layer and lower at the interface with the second nonmagnetic layer. This spatial variation in composition allows different regions of the same layer to serve different functions: the high-boron region reduces saturation magnetization for better write error rate, while the low-boron region maintains retention properties.
Solution Approach 2:
The patent changes the compositional parameter of boron concentration within the ferromagnetic layer to optimize performance. By controlling the boron concentration gradient (higher at one interface, lower at the other), the patent achieves a balance between saturation magnetization and anisotropic magnetic field, thereby simultaneously improving write error rate and maintaining retention properties.
2Duration of action of stationary object
If the film thickness is reduced to improve retention properties, then the write error rate increases
Solution Approach 1:
Instead of uniformly increasing film thickness, the patent uses local quality by varying the boron concentration at different interfaces of the ferromagnetic layer. This allows the thin film to achieve effective magnetization control through compositional grading rather than relying solely on increased thickness, thus maintaining both retention and write performance.
Solution Approach 2:
The patent creates a composite ferromagnetic layer with spatially varying boron concentration, effectively making it a compositionally graded material. This composite structure combines regions of different magnetic properties within a single layer, allowing the thin film to achieve the magnetic moment needed for low write error rate while maintaining the anisotropic field for good retention.
3Duration of action of stationary object
If the anisotropic magnetic field is increased to improve retention properties, then the write current requirement increases
Solution Approach 1:
The patent optimizes the compositional parameter (boron concentration) to achieve a balance between anisotropic magnetic field and saturation magnetization. By carefully controlling the boron gradient, the patent reduces saturation magnetization more than it reduces anisotropic field, thereby lowering the write current requirement while maintaining retention properties.
Solution Approach 2:
The localized boron enrichment at the first interface enhances the perpendicular magnetic anisotropy and reduces saturation magnetization in a targeted manner. This local compositional control allows the patent to reduce write current without significantly compromising the overall retention properties of the magnetoresistive effect element.
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 effectively reduces the product of saturation magnetization and film thickness, enhancing retention properties and write error rates while maintaining high anisotropic magnetic fields, thus improving data storage efficiency.
Implementation Method 1
A magnetic device includes a layer stack including a first ferromagnetic layer, a second ferromagnetic layer, a first nonmagnetic layer between the first ferromagnetic layer and the second ferromagnetic layer, and a second nonmagnetic layer
Implementation Method 2
utilizing magnesium oxide to promote crystallization and interface flatness, allowing for controlled magnetization and improved anisotropic magnetic fields
Data Source
AI summary
According to one embodiment, a magnetic device includes a layer stack. The layer stack includes a first ferromagnetic layer, a second ferromagnetic layer, a first nonmagnetic layer between the first ferromagnetic layer and the second ferromagnetic layer, and a second nonmagnetic layer. The first ferromagnetic layer is interposed between the second nonmagnetic layer and the first nonmagnetic layer. The first nonmagnetic layer and the second nonmagnetic layer contain a magnesium oxide (MgO). The first ferromagnetic layer contains a higher amount of boron (B) at an interface with the first nonmagnetic layer than at an interface with the second nonmagnetic layer.