Zigzag Graphene Nanoribbons: Metallicity Explained

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SUMMARY

Zigzag graphene nanoribbons (GNRs) exhibit metallic properties due to their electronic structure, as confirmed by tight binding theory, which predicts that they are always metallic. In contrast, armchair GNRs can be either metallic or semiconducting based on their width, with density functional theory (DFT) calculations indicating that they are semiconducting with an energy gap inversely related to their width. Experimental results corroborate that energy gaps increase as the width of the GNR decreases, with significant findings including energy gaps of up to 0.5 eV in 2.5 nm wide armchair ribbons. Additionally, zigzag GNRs are characterized by spin-polarized edges, further complicating their classification.

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anahita
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Hi.
Why Zigzag graphene nanoribbons is metallics??
 
Physics news on Phys.org
This may have your answer:

https://en.wikipedia.org/wiki/Graphene_nanoribbons

They state that it depends on several factors:

Electronic structure
...

Calculations based on tight binding theory predict that zigzag GNRs are always metallic[contradictory] while armchairs can be either metallic or semiconducting, depending on their width. However, density functional theory (DFT) calculations show that armchair nanoribbons are semiconducting with an energy gap scaling with the inverse of the GNR width.[18] Experiments verified that energy gaps increase with decreasing GNR width.[19] Graphene nanoribbons with controlled edge orientation have been fabricated by scanning tunneling microscope (STM) lithography.[20] Energy gaps up to 0.5 eV in a 2.5 nm wide armchair ribbon were reported.

Zigzag nanoribbons are semiconducting[contradictory] and present spin polarized edges. ...
 

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