Graphene Spin Device Vertical Electrode Configuration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional spin devices face challenges in achieving high spin-current transfer efficiency and detection sensitivity due to spin scattering and the difficulty in separating electric current and spin current detection regions, especially as devices are miniaturized, leading to low power consumption and integration issues.
Innovation Solution
A spin device utilizing graphene with ferromagnetic electrodes disposed on both surfaces to apply electric current perpendicular to the graphene, allowing for high-sensitivity spin current detection and efficient spin current transfer without electric current interference, enabling low power consumption and high integration density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional spin devices are miniaturized to increase integration density, then device size is reduced, but spin scattering increases and detection sensitivity decreases
Solution Approach 1:
The patent applies dimensionality change by transitioning from in-plane current flow to vertical current flow through the graphene layer. The ferromagnetic electrodes are positioned on opposite surfaces of the graphene, with current flowing perpendicular to the graphene plane. This vertical configuration separates the current path from the spin transport path, enabling high-sensitivity detection even in miniaturized devices by eliminating the geometric constraints that cause spin scattering in conventional in-plane configurations.
Solution Approach 2:
Graphene serves as an intermediary material with exceptional spin transport properties. The patent utilizes graphene's extremely long spin diffusion length and weak spin-orbit coupling to mediate spin transport between ferromagnetic electrodes. This intermediary graphene layer enables efficient spin current transfer and high detection sensitivity while allowing device miniaturization, as the spin information can be transmitted over longer distances without scattering compared to conventional semiconductor materials.
2Device complexity
If ferromagnetic electrodes are disposed on the same surface of graphene, then device structure is simplified, but electric current interferes with spin current detection
Solution Approach 1:
The patent resolves the interference problem by moving the detection electrodes to a different dimension - specifically, placing them on the opposite surface of the graphene relative to the current-injecting ferromagnetic electrodes. This vertical separation in the third dimension (thickness direction) allows spin current to be detected without interference from the electric current path, as the spin diffusion occurs laterally in the graphene plane while the electric current flows vertically through the graphene thickness.
3Length of moving object
If graphene width is reduced to create quantum confinement effect, then energy gap increases for semiconductor behavior, but spin scattering may increase
Solution Approach 1:
The patent utilizes parameter changes by exploiting the unique electronic structure of graphene, specifically its linear band dispersion and Dirac cone structure. By operating near the Dirac point and utilizing the high carrier mobility inherent to graphene's band structure, the device achieves efficient spin transport without requiring large graphene widths. The vertical electrode configuration and operation in the ballistic transport regime allow maintaining low spin scattering even when graphene dimensions are reduced for device integration.
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 spin device achieves enhanced spin-current transfer efficiency and detection sensitivity, enabling low power consumption and high integration density, overcoming the limitations of conventional devices by utilizing graphene and specific electrode configurations.
Implementation Method 1
a first ferromagnetic electrode and a second electrode that are disposed in electrical contact with the graphene in such a manner as to sandwich the graphene; a third ferromagnetic electrode and a fourth electrode that are disposed apart from the first ferromagnetic electrode and the second electrode and in electrical contact with the graphene
Implementation Method 2
Spin scattering occurring in graphene is extremely small compared with that occurring in other materials such as Si and gallium arsenide
Data Source
AI summary
The present disclosure provides a spin device including: a graphene; a first ferromagnetic electrode and a second electrode that are in electrical contact with and sandwich the graphene; a third ferromagnetic electrode and a fourth electrode that sandwich the graphene at a position apart from the first and second electrodes in electrical contact with the graphene; a current applying portion that applies an electric current between the first ferromagnetic electrode and the second electrode; and a voltage-signal detecting portion that detects spin accumulation information as a voltage signal via the third ferromagnetic electrode and the fourth electrode. The spin accumulation information is generated, by application of the electric current, in a part of the graphene that is sandwiched between the third and fourth electrodes. The first and third ferromagnetic electrodes are disposed on the same surface of the graphene, and the second and fourth electrodes are non-magnetic or ferromagnetic electrodes.