Ultrafast formation of a transient two-dimensional diamondlike structure in twisted bilayer graphene

Due to the absence of matching carbon atoms at honeycomb centers with carbon atoms in adjacent graphene sheets, theorists predicted that a sliding process is needed to form AA, AB′, or ABC stacking when directly converting graphite into sp3 bonded diamond. Here, using twisted bilayer graphene, which...

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Bibliographic Details
Published in:Physical review. B 2020-10, Vol.102 (15), p.1, Article 155431
Main Authors: Luo, Duan, Hui, Dandan, Wen, Bin, Li, Renkai, Yang, Jie, Shen, Xiaozhe, Reid, Alexander Hume, Weathersby, Stephen, Kozina, Michael E., Park, Suji, Ren, Yang, Loeffler, Troy D., Sankaranarayanan, S. K. R. S., Chan, Maria K. Y., Wang, Xing, Tian, Jinshou, Arslan, Ilke, Wang, Xijie, Rajh, Tijana, Wen, Jianguo
Format: Article
Language:English
Subjects:
Bilayer films
Bilayers
Carbon
Chemical bonding
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Diamonds
Distribution functions
Dynamical phase transitions
Electron diffraction
Femtosecond laser irradiation
First principles
Graphene
Graphite
Lattice dynamics
Molecular dynamics
Phase transitions
Stacking
Structural phase transition
Structural properties
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Summary:Due to the absence of matching carbon atoms at honeycomb centers with carbon atoms in adjacent graphene sheets, theorists predicted that a sliding process is needed to form AA, AB′, or ABC stacking when directly converting graphite into sp3 bonded diamond. Here, using twisted bilayer graphene, which naturally provides AA and AB′ stacking configurations, we report the ultrafast formation of a transient two-dimensional diamondlike structure (which is not observed in aligned graphene) under femtosecond laser irradiation. This photoinduced phase transition is evidenced by the appearance of bond lengths of 1.94 and 3.14 Å in the time-dependent differential pair distribution function using MeV ultrafast electron diffraction. Molecular dynamics and first-principles calculation indicate that sp3 bonds nucleate at AA and AB′ stacked areas in a moiré pattern. This work sheds light on the direct graphite-to-diamond transformation mechanism, which has not been fully understood for more than 60 years.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.102.155431