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We study magic angle graphene in the presence of both strain and particle-hole symmetry breaking due to non-local inter-layer tunneling. We perform a self-consistent Hartree-Fock study that incorporates these effects alongside realistic…

Electron transport driven by the phase coherence and interference of quantum many-body wavefunctions is a fascinating phenomenon with potential technological significance. Superconductivity, for example, enables dissipationless transport…

Mesoscale and Nanoscale Physics · Physics 2025-04-09 Mainak Das , Chunli Huang

Using scanning probe microscopy and spectroscopy, we explore the spatial symmetry of the electronic wavefunctions of twisted bilayer graphene at the "magic angle" of 1.1 degrees. This small twist angle leads to a long wavelength moir\'e…

Mesoscale and Nanoscale Physics · Physics 2020-08-12 Zhiming Zhang , Rachel Myers , Kenji Watanabe , Takashi Taniguchi , Brian J. LeRoy

Magic-angle twisted bilayer graphene is the best studied physical platform featuring moire potential induced narrow bands with non-trivial topology and strong electronic correlations. Despite their significance, the Chern insulating states…

Mesoscale and Nanoscale Physics · Physics 2024-06-11 Xiaoyu Wang , Oskar Vafek

A variety of new and interesting correlated states have been predicted in graphene monolayer doped to Van Hove singularities (VHSs) of its density-of-state (DOS). However, tuning the Fermi energy to reach a VHS of graphene by either gating…

Mesoscale and Nanoscale Physics · Physics 2017-05-11 Si-Yu Li , Ke-Qin Liu , Long-Jin Yin , Wen-Xiao Wang , Wei Yan , Xu-Qin Yang , Jun-Kai Yang , Haiwen Liu , Hua Jiang , Lin He

Magic-angle twisted bilayer graphene (MATBG) stands as one of the most versatile materials in condensed-matter physics due to its hosting of a wide variety of exotic phases while also offering convenient tunability. However, the fabrication…

Mesoscale and Nanoscale Physics · Physics 2024-05-21 J. Diez-Merida , I. Das , G. Di Battista , A. Diez-Carlon , M. Lee , L. Zeng , K. Watanabe , T. Taniguchi , E. Olsson , D. K. Efetov

Chiral quasiparticles in Bernal-stacked bilayer graphene have valley-contrasting Berry phases of 2{\pi}. This nontrival topological structure, associated with the pseudospin winding along a closed Fermi surface, is responsible for various…

Materials Science · Physics 2020-05-05 Yu Zhang , Ying Su , Lin He

We report on a fully self-consistent Hartree-Fock calculation of interaction effects on the Moir\'e flat bands of twisted bilayer graphene, assuming that valley U(1) symmetry is respected. We use realistic band structures and interactions…

Strongly Correlated Electrons · Physics 2021-10-06 Shang Liu , Eslam Khalaf , Jong Yeon Lee , Ashvin Vishwanath

Moire superlattices in twisted bilayer graphene (TBG) and its derived structures can host exotic correlated quantum phenomena because the narrow moire flat minibands in those systems effectively enhance the electron-electron interaction.…

Materials Science · Physics 2021-10-18 Qiaoling Xu , Yuzheng Guo , Lede Xian

Moire materials exhibit diverse quantum properties such as superconductivity and correlated topo logical phases, making them ideal for studying strongly correlated systems. While moire materials are typically formed by stacking…

Strongly Correlated Electrons · Physics 2024-10-08 Depeng Ji , Qiaoling Xu , Lede Xian

We argue that moir\'e bilayer graphene at charge neutrality hosts a continuous semimetal-to-insulator quantum phase transition that can be accessed experimentally by tuning the twist angle between the two layers. For small twist angles near…

Mesoscale and Nanoscale Physics · Physics 2025-07-10 Jan Biedermann , Lukas Janssen

We study the states localized near an interface between conducting and insulating bilayer graphene (BLG) and show that they have highly unusual properties that have no analog in conventional systems. Moreover, the states belonging to the…

Mesoscale and Nanoscale Physics · Physics 2011-04-20 M. Ahsan Zeb

Magnetotransport of conventional semiconductor based double layer systems with barrier suppressed interlayer tunneling has been a rewarding subject due to the emergence of an interlayer coherent state that behaves as an excitonic…

Mesoscale and Nanoscale Physics · Physics 2025-01-06 Dohun Kim , Seyoung Jin , Takashi Taniguchi , Kenji Watanabe , Jurgen H. Smet , Gil Young Cho , Youngwook Kim

Correlated insulators are frequently observed in magic angle twisted bilayer graphene at even fillings of electrons or holes per moir\'e unit-cell. Whereas theory predicts these insulators to be intervalley coherent excitonic phases, the…

Mesoscale and Nanoscale Physics · Physics 2023-02-15 Gal Shavit , Kryštof Kolář , Christophe Mora , Felix von Oppen , Yuval Oreg

We propose an SU(4) spin-valley-fermion model to investigate the superconducting instabilities of twisted bilayer graphene (TBG). In this approach, bosonic fluctuations associated with an emergent SU(4) symmetry, corresponding to combined…

Superconductivity · Physics 2021-01-20 Yuxuan Wang , Jian Kang , Rafael M. Fernandes

Spin excitations that soften near the onset of magnetic order have long been known to act as `paramagnon' pairing glue that can drive spin-triplet superconductivity. Recent findings of superconductivity in graphene bilayers and trilayers,…

Superconductivity · Physics 2023-06-21 Zhiyu Dong , Leonid Levitov , Andrey V. Chubukov

`More is Different' (Anderson, 1972) in graphene. A bilayer and a twist spring surprises. Recently discovered superconductivity (T$_c\approx$ 1.7 K) at an ultra low doping density $\sim 10^{11}$cm${}^{-2}$ has alerted the community to look…

Superconductivity · Physics 2018-04-03 Ganapathy Baskaran

The non-interacting energy spectrum of graphene and its bilayer counterpart consists of multiple degeneracies owing to the inherent spin, valley and layer symmetries. Interactions among charge carriers are expected to spontaneously break…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 R. Thomas Weitz , Monica T. Allen , Benjamin E. Feldman , Jens Martin , Amir Yacoby

Moir\'e systems have emerged in recent years as a rich platform to study strong correlations. Here, we will discuss a simple, experimentally feasible setup based on periodically strained graphene that reproduces several key aspects of…

Mesoscale and Nanoscale Physics · Physics 2022-11-03 Qiang Gao , Junkai Dong , Patrick Ledwith , Daniel Parker , Eslam Khalaf

To realize the applicative potential of 2D twistronic devices, scalable synthesis and assembly techniques need to meet stringent requirements in terms of interface cleanness and twist-angle homogeneity. Here, we show that small-angle…