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We construct a Wannier basis for twisted bilayer graphene that is projected only from the Bloch functions of the twisted bilayer flat bands. The $C_3$ and $C_{2} \mathcal{T}$ symmetries act locally on the Wannier functions while the Wannier…

Mesoscale and Nanoscale Physics · Physics 2022-10-25 Jiawei Zang , Jie Wang , Antoine Georges , Jennifer Cano , Andrew J. Millis

Twisted graphene bilayers show a complex electronic structure, further modified by interaction effects. The main features can be obtained from effective models, which make use a few phenomenological parameters. We analyze the influence of…

Strongly Correlated Electrons · Physics 2019-03-04 Niels R. Walet , Francisco Guinea

The tight-binding model of bilayer graphene is used to find the gap between the conduction and valence bands, as a function of both the gate voltage and as the doping by donors or acceptors. The total Hartree energy is minimized and the…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 L. A. Falkovsky

Twisted double bilayer graphene (tDBLG) is a moir\'e 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 salient property of the electronic band structure of twisted bilayer graphene (TBG), at the so-called magic angle (MA), is the emergence of flat bands around the charge neutrality point. These bands are associated with the observed…

Mesoscale and Nanoscale Physics · Physics 2023-09-04 Sonia Haddad , Takeo Kato , Jihang Zhu , Lassaad Mandhour

A major hurdle in understanding the phase diagram of twisted bilayer graphene (TBLG) are the roles of lattice relaxation and electronic structure on isolated band flattening near magic twist angles. In this work, the authors develop an…

Mesoscale and Nanoscale Physics · Physics 2024-03-28 Shivesh Pathak , Tawfiqur Rakib , Run Hou , Andriy Nevidomskyy , Elif Ertekin , Harley T. Johnson , Lucas K. Wagner

Moir\'e materials, and in particular twisted bilayer graphene (TBG), exhibit a range of fascinating phenomena, that emerge from the interplay of band topology and interactions. We show that the non-linear second-order photoresponse is an…

Mesoscale and Nanoscale Physics · Physics 2021-07-21 Swati Chaudhary , Cyprian Lewandowski , Gil Refael

We investigate twisted double bilayer graphene (TDBG), a four-layer system composed of two AB-stacked graphene bilayers rotated with respect to each other by a small angle. Our ab initio band structure calculations reveal a considerable…

Mesoscale and Nanoscale Physics · Physics 2020-04-22 Fatemeh Haddadi , QuanSheng Wu , Alex J. Kruchkov , Oleg V. Yazyev

Twisted bilayer graphene exhibits isolated, relatively flat electronic bands near charge neutrality when the interlayer rotation is tuned to specific magic angles. These small misalignments, typically below 1.1{\deg}, result in long-period…

Mesoscale and Nanoscale Physics · Physics 2026-03-26 Antonio Palamara , Michele Pisarra , Antonello Sindona

In twisted bilayer graphene (TBG) a moir\'e pattern forms that introduces a new length scale to the material. At the 'magic' twist angle of 1.1{\deg}, this causes a flat band to form, yielding emergent properties such as correlated…

This work theoretically explores how to emulate twisted double bilayer graphene with ultracold atoms in multiorbital optical lattices. In particular, the quadratic band touching of Bernal stacked bilayer graphene is emulated using a square…

Quantum Gases · Physics 2021-12-28 Junhyun Lee , J. H. Pixley

Twisted bilayer graphene (TBG) exhibits a wide range of intriguing physical properties, such as superconductivity, ferromagnetism, and superlubricity. Depending on the twist angle, periodic moir\'e superlattices form in twisted bilayer…

Mesoscale and Nanoscale Physics · Physics 2022-06-07 Vahid Morovati , Zhiming Xue , Kenneth M. Liechti , Rui Huang

The tight-binding model of a graphene bilayer is used to find the gap between the conduction and valence bands, as a function of both the gate voltage and as the doping by donors or acceptors. The total Hartree energy is minimized and the…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 L. A. Falkovsky

We develop an analytic theory to describe the interaction between electrons and K-phonons and study its influence on superconductivity in the bare bands of twisted bilayer graphene (TBG). We find that, due to symmetry and the two-center…

Superconductivity · Physics 2024-09-10 Chao-Xing Liu , Yulin Chen , Ali Yazdani , B. Andrei Bernevig

We perform unrestricted Hartree-Fock calculations on the 2D Hubbard model on a honeycomb and bilayer honeycomb lattice at both zero and finite temperatures. Finite size real space calculations are supplemented with RPA calculations in the…

Strongly Correlated Electrons · Physics 2026-02-23 Robin Scholle , Laura Classen

Twisted bilayer graphene provides a new two-dimensional platform for studying electron interaction phenomena and flat band properties such as correlated insulator transition, superconductivity and ferromagnetism at certain magic angles.…

Mesoscale and Nanoscale Physics · Physics 2019-07-10 Liheng An , Xiangbin Cai , Meizhen Huang , Zefei Wu , Jiangxiazi Lin , Zhehan Ying , Ziqing Ye , Xuemeng Feng , Ning Wang

We present electronic structure calculations of twisted double bilayer graphene (TDBG): A tetralayer graphene structure composed of two AB-stacked graphene bilayers with a relative rotation angle between them. Using first-principles…

Mesoscale and Nanoscale Physics · Physics 2019-11-05 F. J. Culchac , Rodrigo B. Capaz , Leonor Chico , E. Suarez Morell

We investigate the topological heavy-fermion (THF) model of magic-angle twisted bilayer graphene (MATBG) in the projected limit, where only the flat bands are present in the low-energy spectrum. Such limit has been previously analyzed in…

Strongly Correlated Electrons · Physics 2025-10-20 Haoyu Hu , Zhi-Da Song , B. Andrei Bernevig

We analyze the effects of the long-range Coulomb interaction on the distribution of Berry curvature among the bands near charge neutrality of twisted bilayer graphene (TBG) closely aligned with hexagonal boron nitride (hBN). Due to the…

Mesoscale and Nanoscale Physics · Physics 2022-10-04 Pierre A. Pantaleón , Vo Tien Phong , Gerardo G. Naumis , Francisco Guinea

Through extensive self-consistent Hartree-Fock calculations in a tight-binding model of twisted bilayer graphene (TBG), we show that many-body effects lead to a considerable increase of the bandwidth of the flat bands and, concomitantly, to…

Mesoscale and Nanoscale Physics · Physics 2026-04-30 Miguel Sánchez Sánchez , José González , Tobias Stauber