Experimental Evidence of Chiral Symmetry Breaking in Kekulé-Ordered Graphene

Bao, Changhua; Zhang, Hongyun; Zhang, Teng; Wu, Xi; Luo, Laipeng; Zhou, Shaohua; Li, Qian; Hou, Yanhui; Yao, Wei; Liu, Liwei; Yu, Pu; Li, Jia; Duan, Wenhui; Yao, Hong; Wang, Yeliang

doi:10.1103/physrevlett.126.206804

Cited by 97 publications

(107 citation statements)

References 42 publications

Supporting

Mentioning

101

Contrasting

Order By: Relevance

“…Without √ 3× √ 3 ordering, the STM patterns of TBG display an apparent periodicity corresponding to the usual SLG lattice up to an additional modulation at the moiré scale. In the presence of √ 3 × √ 3 ordering, the apparent periodicity of the graphene mono-layer lattice is broken, with the SLG unit cell becoming enlarged from two to six carbon atoms per unit cell [78,101,102].…”

Section: A General Approximationsmentioning

confidence: 99%

“…In fact, introducing intervalley coherence by means of a U nc (4) rotation in the ground state |ϕ results to intervalley-coherent charge-one excitations, according to the discussion from Appendix [B 4]. In turn, intervalley-coherent charge-one excitations lead to scattering between the two K points of the SLG Brillouin Zone and generically give rise to √ 3 × √ 3 ordering at the level of the SLG lattice [78,101,102]. However, the above reasoning neglects the discrete symmetries of TBG, which impose several restrictions on both the spatial factor and the spectral function matrices.…”

Section: The Spectral Function Of |ψν and Its Unc (4) Rotationsmentioning

confidence: 99%

See 1 more Smart Citation

Spectroscopy of Twisted Bilayer Graphene Correlated Insulators

Călugăru,

Regnault,

et al. 2021

Preprint

View full text Add to dashboard Cite

We calculate STM signatures of correlated ground-states at integer filling of the magic angle twisted bilayer graphene narrow bands. First, we compute the fully-interacting TBG spectral function at ±4 electrons/moiré unit cell and show that it can be used to experimentally validate the strong-coupling approach. Although variation exists in the data, we find experimental evidence for the strong-coupling regime. For all other integer fillings of the flat bands, we consider the spatial features of the corresponding spectral functions of many states in the large degenerate ground-state manifold, and assess the possibility of Kekulé distortion (KD) emerging at the graphene lattice scale. Remarkably, we find that coupling the two opposite graphene valleys in the intervalleycoherent (IVC) TBG insulators does not always result in KD. As an example, we show that the K-IVC state and its nonchiral U (4) rotations do not exhibit any KD, while T-IVC does. We analyze 14 different many-body correlated states and show that their combined STM/Chern number signal can be used to uniquely determine the nature of the many-body ground-state. Their STM signal and features are obtained over a large range of energies and model parameters.

show abstract

Section: A General Approximationsmentioning

confidence: 99%

Section: The Spectral Function Of |ψν and Its Unc (4) Rotationsmentioning

confidence: 99%

Spectroscopy of Twisted Bilayer Graphene Correlated Insulators

Călugăru,

Regnault,

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Experimental studies 1,2 have shown that inducing a Kekulé bond structure in graphene breaks the chiral (valley) symmetry of graphene 3,4 , exhibiting appealing electronic and transport properties. The Kekulé-O (Kek-O) distortion is a periodic modification of the hexagonal bond structure of graphene that leads to the coupling of the two distinct Dirac valleys 5 and effectively folds the graphene Brillouin zone towards its center at the Γ point 6 .…”

Section: Introductionmentioning

confidence: 99%

Valley-driven Zitterbewegung in Kekulé-distorted graphene

Santacruz,

Iglesias,

Carrillo-Bastos

et al. 2021

Preprint

View full text Add to dashboard Cite

Graphene deposited on top of a Copper(111) substrate may develop a Y-shaped Kekulé bond texture (Kekulé-Y), locking the momentum of its Dirac fermions with its valley degree of freedom. As a consequence, the valley degeneracy of its band structure is broken, generating an energy dispersion with two nested Dirac cones with different Fermi velocities. In this work, we investigate the dynamics of electronic wave packets in the Kekulé-Y superlattice. We show that, as a result of the valleymomentum coupling, a valley-driven oscillatory motion of the wave packets (Zitterbewegung) could appear, but with a smaller frequency than the Zitterbewegung effect found pristine graphene. This makes Kekulé-Y graphene a compelling candidate for experimental observation of Zitterbewegung phenomenon in a two-dimensional system.

show abstract

“…We also became aware of Ref. [68], which explores chiral symmetry breaking in Li-intercalated graphene using ARPES and STM measurements.…”

mentioning

confidence: 99%