Narrow bands, electrostatic interactions and band topology in graphene stacks

Pantaleón, Pierre A.; Cea, Tommaso; Brown, R.; Walet, Niels R.; Guinea, F.

doi:10.1088/2053-1583/ac1b6d

Cited by 13 publications

(4 citation statements)

References 75 publications

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“…This explains why significant band deformations are not observed in tDBLG even though the Hartree potential has a similar magnitude as the band width close to the magic angle. A similar explanation for the absence of strong band deformations was also offered in the continuum model of reference [70].…”

Section: Doping Dependent Band Structuresupporting

confidence: 63%

Atomistic Hartree theory of twisted double bilayer graphene near the magic angle

et al. 2022

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Twisted double bilayer graphene (tDBLG) is a moiré material that has recently generated signiﬁcant interest because of the observation of correlated phases near the magic angle. We carry out atomistic Hartree theory calculations to study the role of electron-electron interactions in the normal state. In contrast to twisted bilayer graphene (tBLG), we ﬁnd that such interactions do not result in signiﬁcant doping-dependent deformations of the electronic band structure. However, interactions play an important role for the electronic structure in the presence of a perpendicular electric ﬁeld as they screen the external ﬁeld. Finally, we analyze the contribution of the Hartree potential to the crystal ﬁeld, i.e. the onsite energy diﬀerence between the inner and outer layers. We ﬁnd that the onsite energy obtained from Hartree theory has the same sign, but a smaller magnitude compared to previous studies who determined the onsite energy by ﬁtting tight-binding results to ab initio density-functional theory (DFT) band structures. To understand this quantitative diﬀerence, we analyze the ab initio Kohn-Sham potential obtained from DFT and ﬁnd that a subtle interplay of electron-electron and electron-ion interactions determines the magnitude of the onsite potential.

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Section: Doping Dependent Band Structuresupporting

confidence: 63%

Atomistic Hartree theory of twisted double bilayer graphene near the magic angle

et al. 2022

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“…We have focused on TBG here, but many more moiré materials comprised of graphene exist. [87,88] Perhaps the most promising ones are where there is a ±𝜃 twist between each adjacent graphene layer. [84,[89][90][91][92][93][94][95] These moiré graphene multilayers have been shown to host highly tunable superconducting phases, [96][97][98][99][100] and as the number of layers increases, the superconducting phase occurs over wider and wider doping ranges.…”

Section: Discussionmentioning

confidence: 99%

Short Versus Long Range Exchange Interactions in Twisted Bilayer Graphene

Jimeno‐Pozo

Goodwin

Pantaleón

et al. 2023

Advanced Physics Research

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This study discusses the effect of long‐range interactions within the self‐consistent Hartree‐Fock (HF) approximation in comparison to short‐range atomic Hubbard interactions on the band structure of twisted bilayer graphene (TBG) at charge neutrality for various twist angles. Starting from atomistic calculations, it determines the quasi‐particle band structure of TBG with Hubbard interactions for three magnetic orderings: modulated anti‐ferromagnetic (MAFM), (NAFM) and hexagonal anti‐ferromagnetic (HAFM). Then, it develops an approach to incorporate these magnetic orderings along with the HF potential in the continuum approximation. Away from the magic angle, it observes a drastic effect of the magnetic order on the band structure of TBG compared to the influence of the HF potential. Near the magic angle, the HF potential plays a major role in the band structure, with HAFM and MAFM being secondary effects, but NAFM appears to still significantly distort the electronic structure at the magic angle. These findings suggest that the spin‐valley degenerate broken symmetry state often found in HF calculations of charge neutral TBG near the magic angle should favor magnetic order, since the atomistic Hubbard interaction will break this symmetry in favor of spin polarization.

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“…In twisted bilayer-bilayer graphene, Cao et al found a rich phase diagram with tunable correlated insulator states and spin-polarized phases [9]. Culmination of these recent experimental achievements has motivated theoretical studies on exotic correlated electronic phases in graphene superlattices [10][11][12][13][14][15][16][17].…”

Section: Introduction-mentioning

confidence: 99%

Quantum Monte Carlo study of superconductivity in rhombohedral trilayer graphene under an electric field

Dai¹,

Ma²,

Zhang³

et al. 2022

Preprint

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By using the constrained-phase quantum Monte Carlo method, we performed a systematic study of the ground state of the half-filled Hubbard model for a trilayer honeycomb lattice. We analyse the effect of the perpendicular electric field on the electronic structure, magnetic property and pairing correlations. It is found that antiferromagnetic fluctuations emerge with the perpendicular electric field, and the electronic correlation drives a d + id superconducting pairing to be dominant over other pairing patterns among various electric fields and interaction strengths. We also found that the d + id pairing correlation is greatly enhanced as the on-site Coulomb interaction is increased. Our intensive numerical results may unveil the nature of the recently observed superconductivity in rhombohedral trilayer graphene under an electric field.

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Narrow bands, electrostatic interactions and band topology in graphene stacks

Cited by 13 publications

References 75 publications

Atomistic Hartree theory of twisted double bilayer graphene near the magic angle

Atomistic Hartree theory of twisted double bilayer graphene near the magic angle

Short Versus Long Range Exchange Interactions in Twisted Bilayer Graphene

Quantum Monte Carlo study of superconductivity in rhombohedral trilayer graphene under an electric field

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