Exploring Graphene Nanoribbon Based Composites and its Applications

Carbon based material has been observed as the frontier area of research and prospective material for technological solicitations since last decade.The competence of forming different architect at nanoscale makes carbon a versatile and unique element. Carbon in many forms has been investigated as electromagnetic interference (EMI) materials, in electrode science and technology, solar cells, biomedical applications, sensing, and so on, where different carbon structures provide different properties due to its flexibility to be transformed into different forms via its different degrees of hybridization. 

In this family of carbon based nanostructures, Graphene is a recent addition with extraordinary electronic, mechanical and optical properties. Graphene nano ribbons (GNRs) are special allotropes of carbon which have completely different electronic and mechanical properties than its parent structure i.e. graphene or carbon nanotubes.Change in the dimension of sheet from graphene to GNR leads to the change in the physical, chemical, optical, electronic, mechanical properties of the material which are otherwise considered intensive in nature. Recent studies have shown the robustness of edge states to changes in their size and geometry. Since the structural or chemical modification of graphene edges affects the electronic states near the Fermi energy, they can be used to design and bring functionality in the nanocarbon systems. 

One of the concern of modern development is design and manufacturing of electronic devices in higher frequency range without being affected by electromagnetic interference (EMI). The need for developing versatile and efficient shielding material for commercial, military and electronic and communication instruments is increasing. Carbon-based polymer composites are found to be attractive due to their exceptional properties like low density, good electrical and mechanical properties,ease in processibility and so on.

Depending on the synthesis method employed GNR shows distinct edge dependent electronic properties.  It is the change in properties in GNR and its composites that has driven us to exploit it and use it for applications like EMI shielding. Probe microscopy techniques mainly (Scanning tunneling Microscope, Atomic Force Microscope, Conducting force Microscope, Magnetic force Microscope) are one of the promising technique to check the electronic properties of GNR at local level. In the context of EMI shielding properties of GNR, we demonstrated how the edge dependent electronic properties and the presence of localized state near the Fermi level provides the spin states required for absorbance of radiations and thereby helping the use of GNR and its composites for shielding in X- band of the electromagnetic spectrum.

Another property of GNR which is extensively studied theoretically is its magnetic properties. It has been shown using DFT that GNR has ferromagnetically aligned spins along the edges and antiferromagetically aligned along opposite edges. To explore these properties we have studied a conjugated system of GNR-LSMO (10%) extensively using MFM. Some preliminary results will be shown in the presentation.

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