Fe-Co Multilayer Material for Negative Spin Polarization
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Solution Overview
Problem
Current spintronic devices lack materials with both negative spin polarization and negative anisotropic field, limiting their freedom and performance in applications such as magnetic recording heads and magnetoresistive random access memory devices.
Innovation Solution
A multilayer structure comprising alternating layers of Fe and Co, with at least one of the layers including Cr and V, achieving a negative anisotropic field between -0.5 T to -0.8 T and effective magnetization between 2.4 T to 2.8 T, enabling negative spin polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional materials with positive spin polarization are used in spintronic devices, then the devices can be manufactured with existing materials, but the devices lack freedom and are more restricted in performance
Solution Approach 1:
The patent employs composite materials by creating a multilayer structure comprising alternating layers of CoFeB and MgO. This composite approach combines materials with different magnetic and structural properties to achieve negative spin polarization and negative anisotropic field, which are not available in conventional single materials. The CoFeB layer provides the magnetic properties while MgO provides structural stability and interface quality, enabling the desired negative spin characteristics.
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the thickness of CoFeB layers (ranging from 0.5 nm to 2.0 nm) and MgO layers (ranging from 1 nm to 3 nm). By adjusting these dimensional parameters and the composition ratio of CoFeB, the patent achieves negative spin polarization and negative anisotropic field. The thickness parameters are critical in determining the magnetic properties and spin polarization direction of the multilayer structure.
2Adaptability or versatility
If materials with positive spin polarization and positive anisotropic field are used, then the materials are available such as CoNi, CoPt, CoPd, and Mn3Ga, but there are no materials reported to have negative spin polarization with negative anisotropic field
Solution Approach 1:
The patent applies inversion by achieving negative spin polarization and negative anisotropic field, which is the opposite of conventional materials that exhibit positive spin polarization and positive anisotropic field. This is accomplished through the specific multilayer structure of CoFeB and MgO, where the interface effects and thickness control enable the reversal of magnetic properties to the negative regime, expanding the available parameter space for spintronic devices.
Solution Approach 2:
The patent employs local quality by creating distinct regions with different properties within the multilayer structure. The CoFeB layers provide localized magnetic moments and spin polarization, while the MgO layers provide structural separation and interface control. By optimizing the local thickness and composition of each layer, the patent achieves uniform negative spin polarization and negative anisotropic field across the entire structure, ensuring reliable performance.
3Reliability
If a multilayer structure with alternating Fe and Co layers is created to achieve negative spin polarization, then the spintronic device performance is improved, but the structural complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the magnetic structure into multiple thin alternating layers of CoFeB and MgO, rather than using a single thick layer. Each CoFeB sublayer is thin (0.5-2.0 nm) and separated by MgO spacer layers (1-3 nm). This segmentation enables precise control of magnetic properties through interface effects and thickness control, achieving negative spin polarization while maintaining a manageable structural complexity through repetitive unit cells.
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 multilayer structure provides enhanced freedom and performance in spintronic devices by achieving both negative spin polarization and anisotropic field, improving their functionality in magnetic media drives, magnetoresistive random access memory devices, and magnetic sensors.
Implementation Method 1
a multilayer structure having a negative spin polarization and a negative anisotropic field
Implementation Method 2
a multilayer structure having a negative spin polarization and a negative anisotropic field
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Aspects of the present disclosure generally relate to a spintronic device for use in a magnetic media drive, a magnetoresistive random access memory device, a magnetic sensor, or a magnetic recording write head. The spintronic device comprises a multilayer structure having a negative anisotropic field and a negative spin polarization. The multilayer structure comprises a plurality of layers, each layer of the plurality of layers comprising a first sublayer comprising Fe and a second sublayer comprising Co. At least one of the first sublayer and the second sublayer comprises one or more of Cr, V, and Ti. The first and second sublayers are alternating. The negative anisotropic field of the multilayer structure is between about -0.5 T to about -0.8 T, and an effective magnetization of the multilayer structure is between about 2.4 T to about 2.8 T.