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We introduce a novel two-dimensional electronic system with ultrastrong interlayer interactions, namely twisted bilayer graphene with a large twist angle, as an ideal ground for realizing interlayer-coherent excitonic condensates. In these…

Mesoscale and Nanoscale Physics · Physics 2022-12-20 Dohun Kim , Byungmin Kang , Yong-Bin Choi , Kenji Watanabe , Takashi Taniguchi , Gil-Ho Lee , Gil Young Cho , Youngwook Kim

Proximity effects resulting from depositing a graphene layer on a TMD substrate layer change the dynamics of the electronic states in graphene, inducing spin orbit coupling (SOC) and staggered potential effects. An effective Hamiltonian…

Mesoscale and Nanoscale Physics · Physics 2016-12-21 Abdulrhman M. Alsharari , Mahmoud M. Asmar , Sergio E. Ulloa

We use stochastic expansion and exact diagonalization to study the magic-angle twisted bilayer graphene (TBG) on a disordered substrate. We show that the substrate-induced strong Coulomb disorder in TBG with the chemical potential at the…

Disordered Systems and Neural Networks · Physics 2023-08-09 Chenan Wei , Tigran A. Sedrakyan

We study the emergence of strongly correlated states and Kondo physics in disordered graphene. Diluted short range disorder gives rise to localized midgap states at the vicinity of the system charge neutrality point. We show that long-range…

Mesoscale and Nanoscale Physics · Physics 2014-11-20 Vladimir G. Miranda , Luis G. G. V. Dias da Silva , Caio H. Lewenkopf

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

We study the electron-phonon coupling in twisted bilayer graphene (TBG), which was recently experimentally observed to exhibit superconductivity around the magic twist angle $\theta\approx 1.05^\circ$. We show that phonon-mediated electron…

Mesoscale and Nanoscale Physics · Physics 2019-07-03 Biao Lian , Zhijun Wang , B. Andrei Bernevig

Twisted bilayer graphene (TBG) has attracted great interest in the last decade due to the novel properties it exhibited. It was revealed that e-phonon interaction plays an important role in a variety of phenomena in this system, such as…

Mesoscale and Nanoscale Physics · Physics 2024-10-29 Jun-Wei Li , Jia-Xing Zhang , Wei Chen

Magic angle twisted bilayer graphene (MATBG) hosts narrow moir\'e bands with meV-scale energy splittings, making its correlated phases sensitive to both material parameters and modeling choices in low-energy downfolding. We develop an ab…

Strongly Correlated Electrons · Physics 2026-03-12 Raehyun Kim , Woochang Kim , Kevin D. Stubbs , Steven G. Louie , Lin Lin

Twisted graphene bilayers (TGBs) have low-energy van Hove singularities (VHSs) that are strongly localized around AA-stacked regions of the moire pattern. Therefore, they exhibit novel many-body electronic states, such as Mott-like…

Mesoscale and Nanoscale Physics · Physics 2019-05-15 Yi-Wen Liu , Jia-Bin Qiao , Chao Yan , Yu Zhang , Si-Yu Li , Lin He

In the vicinity of the magic angle in twisted bilayer graphene (TBG), the two low-energy van Hove singularities (VHSs) become exceedingly narrow1-10 and many exotic correlated states, such as superconductivity, ferromagnetism, and…

Strongly Correlated Electrons · Physics 2020-02-25 Yu Zhang , Zhe Hou , Ya-Xin Zhao , Zi-Han Guo , Yi-Wen Liu , Si-Yu Li , Ya-Ning Ren , Qing-Feng Sun , Lin He

Realizations of some topological phases in two-dimensional systems rely on the challenge of jointly incorporating spin-orbit and magnetic exchange interactions. Here, we predict the formation and control of a fully valley-polarized quantum…

Mesoscale and Nanoscale Physics · Physics 2021-10-25 Marc Vila , Jose H. Garcia , Stephan Roche

Twisted homobilayer transition metal dichalcogenide (TMD) offers a versatile platform for exploring band topology, interaction-driven phases, and magnetic orders. We study the interaction-driven phases in twisted TMD homobilayers and their…

Strongly Correlated Electrons · Physics 2024-09-12 Taige Wang , Trithep Devakul , Michael P. Zaletel , Liang Fu

We study the Kondo physics of a quantum magnetic impurity in two-dimensional topological superconductors (TSCs), either intrinsic or induced on the surface of a bulk topological insulator, using a numerical renormalization group technique.…

Superconductivity · Physics 2019-03-06 Rui Wang , W. Su , Jian-Xin Zhu , C. S. Ting , Hai Li , Changfeng Chen , Baigeng Wang , Xiaoqun Wang

We show that the electronic structure of the low-energy bands in the small angle-twisted bilayer graphene consists of a series of semi-metallic and topological phases. In particular we are able to prove, using an approximate low-energy…

Mesoscale and Nanoscale Physics · Physics 2019-07-24 Zhida Song , Zhijun Wang , Wujun Shi , Gang Li , Chen Fang , B. Andrei Bernevig

We analytically compute the scanning tunneling microscopy (STM) signatures of integer-filled correlated ground states of the magic angle twisted bilayer graphene (TBG) narrow bands. After experimentally validating the strong-coupling…

We have carried out ab initio electronic structure calculations on graphane (hydrogenated graphene) with single and double vacancy defects. Our analysis of the density of states reveal that such vacancies induce the mid gap states and…

Materials Science · Physics 2010-02-11 Bhalchandra S. Pujari , D. G. Kanhere

Magic-angle twisted bilayer graphene (MA-TBG) exhibits intriguing quantum phase transitions triggered by enhanced electron-electron interactions when its flat-bands are partially filled. However, the phases themselves and their connection…

Mesoscale and Nanoscale Physics · Physics 2021-04-14 Shuang Wu , Zhenyuan Zhang , K. Watanabe , T. Taniguchi , Eva Y. Andrei

Based on ab-initio calculations we identify possible scenarios for the Kondo effect due to Co ad-atoms on graphene. General symmetry arguments show that for magnetic atoms in high-symmetry positions, the Kondo effect in graphene is…

Strongly Correlated Electrons · Physics 2010-03-22 T. O. Wehling , A. V. Balatsky , M. I. Katsnelson , A. I. Lichtenstein , A. Rosch

Magic-angle twisted bilayer graphene (MATBG) exhibits a rich variety of electronic states, including correlated insulators, superconductors, and topological phases. Understanding the microscopic mechanisms responsible for these phases…

Magic-angle twisted bilayer graphene (MATBG) is notable as a highly tunable platform for investigating strongly correlated phenomena such as high-$T_c$ superconductivity and quantum spin liquids, due to easy control of doping level through…

Mesoscale and Nanoscale Physics · Physics 2020-06-04 Xiao Chen , Shuanglong Liu , James N Fry , Hai-Ping Cheng