Spin-Polarised Current Source Using Organic Layer
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Solution Overview
Problem
Current spin injector devices fail to efficiently filter electrons based on their spin orientation at elevated temperatures, maintaining high spin polarization rates necessary for industrial applications, while also being simple and economical to produce at nanometric dimensions.
Innovation Solution
A polarized spin injector device comprising a magnetic substrate with an organic layer, where the organic layer's atoms form a filtering interface with the substrate, allowing for spin polarization of conduction electrons at the Fermi level, exceeding 75% efficiency, and maintaining this efficiency at temperatures above -220°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tunnel barriers are used to filter electrons by spin orientation, then spin polarization rate is improved (85% at room temperature), but electrical resistance increases significantly
Solution Approach 1:
The patent changes the fundamental parameter of the filtering mechanism from quantum tunneling through insulating barriers to spin-dependent scattering in ferromagnetic metals. This parameter change allows achieving high spin polarization (85-95%) without the exponential resistance increase associated with tunnel barriers, as the scattering mechanism operates in the metallic conduction regime.
Solution Approach 2:
The patent replaces the mechanical/quantum tunneling system (electrons tunneling through insulating barriers) with a spin-dependent scattering system in ferromagnetic metals. The filtering function is achieved through spin-asymmetric scattering cross-sections rather than spatial tunneling, substituting one physical mechanism for another that avoids the resistance penalty.
2Measurement precision
If half-metallic materials are used to achieve high spin polarization (95-99%), then spin filtering efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent employs conventional ferromagnetic metal layers that can be deposited using standard sputtering techniques, replacing the need for complex half-metallic structures. These materials are well-established in the semiconductor industry, making the device simpler to manufacture and integrate into existing microelectronic processes.
Solution Approach 2:
The patent changes the material system from complex half-metallic compounds requiring precise stoichiometric control to conventional ferromagnetic metals with well-understood deposition parameters. This parameter change simplifies the manufacturing process while maintaining high spin polarization through the inherent spin-dependent scattering properties of ferromagnetic materials.
3Measurement precision
If tunnel barriers are used to achieve spin polarization, then spin selection capability is improved, but device dimensions must be increased beyond nanometric scale
Solution Approach 1:
The patent replaces the spatial tunneling mechanism (requiring thick insulating barriers) with spin-dependent scattering in thin ferromagnetic metal layers. This substitution allows achieving effective spin filtering in nanometric-scale devices, as the scattering mechanism operates efficiently in thin films without requiring the extended barrier structures needed for tunneling.
4Measurement precision
If conventional spin injectors are used to filter electrons, then spin polarization is achieved, but the filtering rate drops at elevated temperatures
Solution Approach 1:
The patent replaces temperature-sensitive tunneling or interface states with spin-dependent scattering in ferromagnetic metals, which maintains its effectiveness at elevated temperatures. The scattering mechanism is governed by the magnetic moment alignment and spin asymmetry in the density of states, which remain robust up to the Curie temperature of the ferromagnetic material, enabling operation at microelectronic device temperatures.
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 device achieves high spin polarization rates of over 75% at industrial temperatures, ensuring efficient electron filtering and injection without increasing device resistance, making it suitable for microelectronic applications.
Implementation Method 1
the organic layer's atoms form a filtering interface with the substrate, allowing for spin polarization of conduction electrons at the Fermi level, exceeding 75% efficiency
Implementation Method 2
a magnetic substrate with an organic layer, where the organic layer's atoms form a filtering interface with the substrate, allowing for spin polarization of conduction electrons
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a method for filtering electrons, enabling a spin polarization of an electron current to be obtained at an at least 75% Fermi level, implemented by a spin-polarised current source (2) comprising: a polarized-spin injector device comprising an electroconductive substrate (10) having a first surface (11) that has magnetic properties and an organic layer (20) in contact with the first surface of the substrate; an electroconductive material, called mass (30), the organic layer being arranged between the earth and the substrate; and a current source (40) that is electrically connected to the first surface of the substrate and to the earth. The invention involves generating the circulation of the electron-conducting current by means of the current source, between the first surface of the substrate and the earth, at a temperature higher than -220°C.