研究目的
Investigating the electronic states at graphene edges using field emission microscopy (FEM) and field ion microscopy (FIM), and measuring the spin polarization of electrons field-emitted from graphene edges.
研究成果
The study successfully observed the spatial distribution of π-orbitals at graphene edges using FEM and FIM, with FIM providing higher resolution. Preliminary measurements of spin polarization showed values of 20 to 25% at room temperature, indicating the potential for graphene edges in spintronics applications. However, the effect of residual gas adsorption on spin polarization requires further investigation.
研究不足
The study is limited by the potential adsorption of residual gas species such as hydrogen, which can affect the spin polarization measurements. The abrupt decrease in spin polarization observed may be due to such adsorptions.
1：Experimental Design and Method Selection:
The study employs FEM and FIM to investigate graphene edges at an atomic scale, focusing on the spatial distribution of π-orbitals and spin polarization of emitted electrons.
2：Sample Selection and Data Sources:
Graphene emitters were prepared by two methods: a scratching method using a graphite crystal and electrophoretic deposition using an aqueous suspension of graphene oxide.
3：List of Experimental Equipment and Materials:
Equipment includes a scanning electron microscope, micro-manipulators, a tungsten needle, and a Mott spin polarization analyzer. Materials include graphene oxide and highly oriented pyrolytic graphite (HOPG).
4：Experimental Procedures and Operational Workflow:
FEM and FIM measurements were carried out on the same graphene edge. Spin polarization measurements were performed using a FEM equipped with a spin rotator and a Mott analyzer.
5：Data Analysis Methods:
The spin polarization magnitude was calculated using the vector sum of all components, with measurements taken at room temperature in ultra-high vacuum.
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