Lattice relaxation, mirror symmetry and magnetic field effects on ultraflat bands in twisted trilayer graphene

Wu, Zewen; Zhan, Zhen; Yuan, Shengjun

doi:10.1007/s11433-020-1690-4

Cited by 32 publications

(25 citation statements)

References 47 publications

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“…1(c) for V ¼ 0. We highlight the emergence of flat bands, similar to the ones observed in twisted bilayer graphene at the magic angle, coexisting with dispersive modes [25][26][27][28]38]. Interestingly, when applying an interlayer bias, this twisted system develops even flatter bands, as shown in Fig.…”

supporting

confidence: 64%

“…More complex twisted graphene multilayers, such as twisted bi-bilayers [7,10] and trilayers [21][22][23], have provided additional platforms to realize similar physics as twisted graphene bilayers. The possibility of tuning several twist angles in multilayer graphene [24][25][26][27][28] suggests that these systems may realize correlated states of matter beyond the ones already observed in twisted bilayers.…”

mentioning

confidence: 98%

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Emulating Heavy Fermions in Twisted Trilayer Graphene

Ramires

Lado

2021

Phys. Rev. Lett.

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Twisted van der Waals materials have been shown to host a variety of tunable electronic structures. Here we put forward twisted trilayer graphene (TTG) as a platform to emulate heavy fermion physics. We demonstrate that TTG hosts extended and localized modes with an electronic structure that can be controlled by interlayer bias. In the presence of interactions, the existence of localized modes leads to the development of local moments, which are Kondo coupled to coexisting extended states. By electrically controlling the effective exchange between local moments, the system can be driven from a magnetic into a heavy fermion regime, passing through a quantum critical point, allowing one to electrically explore a generalized Doniach phase diagram. Our results put forward twisted graphene multilayers as a platform for the realization of strongly correlated heavy fermion physics in a purely carbon-based platform.

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confidence: 64%

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confidence: 98%

Emulating Heavy Fermions in Twisted Trilayer Graphene

Ramires

Lado

2021

Phys. Rev. Lett.

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“…This symmetry can be broken by various experimentally-relevant perturbations. In this case, calculations of the electronic structure in the absence of this mirror symmetry shows hybridized monolayer and twisted bilayer features [3,[23][24][25][26][27]. The effect of electron-electron interactions have also been considered [24][25][26][27][28][29][30], as well as the role of external magnetic fields [31].…”

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confidence: 99%

Band Structure and Superconductivity in Twisted Trilayer Graphene

Phong,

Pantaleón,

Cea

et al. 2021

Preprint

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We study the symmetries of twisted trilayer graphene's band structure under various extrinsic perturbations, and analyze the role of long-range electron-electron interactions near the first magic angle. The electronic structure is modified by these interactions in a similar way to twisted bilayer graphene. We analyze electron pairing due to long-wavelength charge fluctuations, which are coupled among themselves via the Coulomb interaction and additionally mediated by longitudinal acoustic phonons. We find superconducting phases with either spin singlet/valley triplet or spin triplet/valley singlet symmetry, with critical temperatures of up to a few Kelvin for realistic choices of parameters.

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“…Moiré potentials obtained in graphene multi-layer structures by slight misalignment of the stacked layers have proven remarkably fruitful for tuning the singleparticle spectrum [6][7][8] and thereby achieving exotic phases driven by the combined effects of electronic correlation and topology [9,10]. Twisted bilayer graphene (TBG) with two rotated graphene sheets thus exhibits a plethora of interesting phases [11], including correlated symmetry breaking insulators [12][13][14][15][16][17], signatures of fragile topology [18,19], orbital magnetism [20][21][22][23][24] and Chern insulators [25][26][27][28] with a quantum anomalous Hall effect [29][30][31], nematicity [32,33], and superconductivity [10,22,34]. Significant theoretical progress has been also achieved, especially in understanding the competing non-superconducting phases, see for instance Refs.…”

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confidence: 99%

Higher-order van Hove singularity in magic-angle twisted trilayer graphene

Guerci,

Simon,

Mora

2021

Preprint

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We study the presence of higher-order van Hove singularities in mirror-symmetric twisted trilayer graphene. This geometry has recently emerged experimentally as a fascinating playground for studying correlated and exotic superconducting phases. We find that the trilayer hosts a zeroenergy higher-order van Hove singularity with an exponent −1/3. The singularity is protected by the threefold rotation symmetry and a combined mirror-particle-hole symmetry and it can be tuned with only the twist angle and a perpendicular electric field. It arises from the combined merging of van Hove singularities and Dirac cones at zero energy, beyond the recent classifications of van Hove singularities. Moreover, we find that varying a third parameter such as corrugation brings the system to a topological Lifshitz transition, with anomalous exponent −2/5, separating regions of locally open and closed semiclassical orbits.

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Lattice relaxation, mirror symmetry and magnetic field effects on ultraflat bands in twisted trilayer graphene

Cited by 32 publications

References 47 publications

Emulating Heavy Fermions in Twisted Trilayer Graphene

Emulating Heavy Fermions in Twisted Trilayer Graphene

Band Structure and Superconductivity in Twisted Trilayer Graphene

Higher-order van Hove singularity in magic-angle twisted trilayer graphene

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