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Inversion Symmetry-Broken Tetralayer Graphene Probed by Second-Harmonic Generation.
Wenqiang Zhou1,2,3, Jiannan Hua2,3, Naitian Liu2,3
1School of Physics, Zhejiang University, Hangzhou 310027, China.
Nano Letters
|June 17, 2024
Summary
We observed nonlinear optical second-harmonic generation (SHG) in ABCB-stacked tetralayer graphene, confirming symmetry breaking. This finding highlights ABCB-stacked graphene as a platform for studying elemental ferroelectricity.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Stacking order in 2D materials tunes their properties.
- ABCB-stacked tetralayer graphene was theoretically predicted to exhibit ferroelectricity due to symmetry breaking.
- Experimental exploration of this phenomenon has been limited.
Purpose of the Study:
- To experimentally investigate the predicted ferroelectricity in ABCB-stacked tetralayer graphene.
- To explore the potential of nonlinear optical techniques for characterizing stacking orders.
- To establish ABCB-stacked graphene as a platform for studying elemental ferroelectricity.
Main Methods:
- Utilizing second-harmonic generation (SHG) spectroscopy.
- Comparing SHG signals in ABCB-, ABAB-, and ABCA-stacked tetralayer graphene.
- Analyzing SHG spectra to identify stacking order and crystalline orientation.
Main Results:
- Pronounced nonlinear optical SHG was observed in ABCB-stacked tetralayer graphene.
- SHG was absent in ABAB- and ABCA-stacked tetralayer graphene.
- Distinct SHG spectra enabled straightforward identification of ABCB domains.
Conclusions:
- The observed SHG provides direct evidence of symmetry breaking in ABCB-stacked tetralayer graphene.
- SHG is a convenient tool for identifying stacking order and studying ferroelectricity in graphene.
- ABCB-stacked graphene offers a unique platform for exploring ferroelectricity in noncentrosymmetric elemental structures.
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