Chin. Phys. Lett.  2022, Vol. 39 Issue (7): 077301    DOI: 10.1088/0256-307X/39/7/077301
 CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
Spectroscopic Evidence for Electron Correlations in Epitaxial Bilayer Graphene with Interface-Reconstructed Superlattice Potentials
Chaofei Liu1 and Jian Wang1,2,3*
1International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
2CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
3Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Chaofei Liu and Jian Wang 2022 Chin. Phys. Lett. 39 077301
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Abstract Superlattice potentials are theoretically predicted to modify the single-particle electronic structures. The resulting Coulomb-interaction-dominated low-energy physics would generate highly novel many-body phenomena. Here, by in situ tunneling spectroscopy, we show the signatures of superstructure-modulated correlated electron states in epitaxial bilayer graphene (BLG) on 6H-SiC(0001). As the carrier density is locally quasi-‘tuned’ by the superlattice potentials of a $6 \times 6$ interface reconstruction phase, the spectral-weight transfer occurs between the two broad peaks flanking the charge-neutral point. Such a detected non-rigid band shift beyond the single-particle band description implies the existence of correlation effects, probably attributed to the modified interlayer coupling in epitaxial BLG by the $6 \times 6$ reconstruction as in magic-angle BLG by the moiré potentials. Quantitative analysis suggests that the intrinsic interface reconstruction shows a high carrier tunability of $\sim$1/2 filling range, equivalent to the back gating by a voltage of $\sim$70 V in a typical gated BLG/SiO$_{2}$/Si device. The finding in interface-modulated epitaxial BLG with reconstruction phase extends the BLG platform with electron correlations beyond the magic-angle situation, and may stimulate further investigations on correlated states in graphene systems and other van der Waals materials.
Received: 20 April 2022      Editors' Suggestion Published: 18 June 2022
 PACS: 73.21.Cd (Superlattices) 73.22.Pr (Electronic structure of graphene) 68.37.Ef (Scanning tunneling microscopy (including chemistry induced with STM))
 TRENDMD: URL: http://cpl.iphy.ac.cn/10.1088/0256-307X/39/7/077301       OR      http://cpl.iphy.ac.cn/Y2022/V39/I7/077301