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Twisted bilayer graphene (TBG) provides a unique framework to elucidate the interplay between strong correlations and topological phenomena in two-dimensional systems. The existence of multiple electronic degrees of freedom -- charge, spin,…

Strongly Correlated Electrons · Physics 2021-01-27 Yuan Da Liao , Jian Kang , Clara N. Breiø , Xiao Yan Xu , Han-Qing Wu , Brian M. Andersen , Rafael M. Fernandes , Zi Yang Meng

The polarizability of twisted bilayer graphene, due to the combined effect of electron-hole pairs, plasmons, and acoustic phonons is analyzed. The screened Coulomb interaction allows for the for- mation of Cooper pairs and superconductivity…

Strongly Correlated Electrons · Physics 2021-08-12 Tommaso Cea , Francisco Guinea

We analyze the dissipative conductance of the zero-plateau quantum Hall state appearing in undoped graphene in strong magnetic fields. Charge transport in this state is assumed to be carried by a magnetic domain wall, which forms by…

Mesoscale and Nanoscale Physics · Physics 2009-06-02 Efrat Shimshoni , H. A. Fertig , G. Venketeswara Pai

We identify states favored by Coulomb interactions projected onto the Wannier basis of the four narrow bands of the "magic angle" twisted bilayer graphene. At the filling of two electrons/holes per moire unit cell, such interactions favor…

Strongly Correlated Electrons · Physics 2019-06-20 Jian Kang , Oskar Vafek

Bilayer graphene in a magnetic field supports eight zero-energy Landau levels, which, as a tunable band gap develops, evolve into two nearly-degenerate quartets separated by the band gap. A close look is made into the properties of such an…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 K. Shizuya

The strong long-range Coulomb interaction between massless Dirac fermions in graphene can drive a semimetal-insulator transition. We show that this transition is strongly suppressed when the Coulomb interaction is screened by such effects…

Strongly Correlated Electrons · Physics 2015-05-13 Guo-Zhu Liu , Wei Li , Geng Cheng

We have studied the interplay of valley polarization and the Coulomb interaction on the energy spectrum, persistent current, and optical absorption of a graphene quantum ring. We show that the interaction has a dramatic effect on the nature…

Mesoscale and Nanoscale Physics · Physics 2008-06-18 D. S. L. Abergel , Vadim M. Apalkov , Tapash Chakraborty

Spatially separated electron systems remain strongly coupled by electron-electron interactions even when they cannot exchange particles, provided that the layer separation d is comparable to a characteristic distance l between charge…

We address the question of the stability of the (fractional) quantum Hall effect (QHE) in presence of pseudomagnetic disorder generated by mechanical deformations of a graphene sheet. Neglecting the potential disorder and taking into…

Mesoscale and Nanoscale Physics · Physics 2017-04-05 Andrey A. Bagrov , Alessandro Principi , Mikhail I. Katsnelson

Here we study the evolution of local electronic properties of a twisted graphene bilayer induced by a strain and a high curvature. The strain and curvature strongly affect the local band structures of the twisted graphene bilayer; the…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 Wei Yan , Wen-Yu He , Zhao-Dong Chu , Mengxi Liu , Lan Meng , Rui-Fen Dou , Yanfeng Zhang , Zhongfan Liu , Jia-Cai Nie , Lin He

The recent synthesis of two-dimensional staggered materials opens up burgeoning opportunities to study optical spin-orbit interactions in semiconducting Dirac-like systems. We unveil topological phase transitions in the photonic spin Hall…

Mesoscale and Nanoscale Physics · Physics 2017-10-11 W. J. M. Kort-Kamp

We study strongly correlated ground states of dipolar fermions in a honeycomb optical lattice with spatial variations in hopping amplitudes. Similar to a strained graphene, such nonuniform hopping amplitudes produce valley-dependent…

Quantum Gases · Physics 2016-11-02 Hiroyuki Fujita , Yuya O. Nakagawa , Yuto Ashida , Shunsuke Furukawa

We investigate an effective model of proximity modified graphene (or symmetrylike materials) with broken time-reversal symmetry. We predict the appearance of quantum anomalous Hall phases by computing bulk band gap and Chern numbers for…

Mesoscale and Nanoscale Physics · Physics 2020-04-07 Petra Högl , Tobias Frank , Klaus Zollner , Denis Kochan , Martin Gmitra , Jaroslav Fabian

Many-body interactions in topological quantum systems can give rise to new phases of matter, which simultaneously exhibit both rich spatial features and topological properties. In this work, we consider spinless fermions on a checkerboard…

Quantum Gases · Physics 2020-12-10 Sergi Julià-Farré , Markus Müller , Maciej Lewenstein , Alexandre Dauphin

We study an extended Hubbard model with the nearest-neighbor Coulomb interaction on the pyrochlore lattice at half filling. An interaction-driven insulating phase with nontrivial Z_2 invariants emerges at the Hartree-Fock mean-field level…

Strongly Correlated Electrons · Physics 2015-05-20 Moyuru Kurita , Youhei Yamaji , Masatoshi Imada

Strain-induced pseudo-magnetic fields can mimic real magnetic fields to generate a zero-magnetic-field analogue of the Landau levels (LLs), i.e., the pseudo-LLs, in graphene. The distinct nature of the pseudo-LLs enables one to realize…

Mesoscale and Nanoscale Physics · Physics 2022-08-17 Yi-Wen Liu , Zhen Zhan , Zewen Wu , Chao Yan , Shengjun Yuan , Lin He

With the recent observation of graphene-like Landau levels at the surface of topological insulators, the possibility of fractional quantum Hall effect, which is a fundamental signature of strong correlations, has become of interest. Some…

Mesoscale and Nanoscale Physics · Physics 2013-05-21 Ashley M. DaSilva

We describe the formation of superconducting states in graphene in the presence of pseudo-Landau levels induced by strain, when time reversal symmetry is preserved. We show that superconductivity in strained graphene is quantum critical…

Superconductivity · Physics 2013-07-29 Bruno Uchoa , Yafis Barlas

In the quantum Hall regime of graphene, antiferromagnetic and spin-polarized ferromagnetic states at the zeroth Landau level compete, leading to a canted antiferromagnetic state depending on the direction and magnitude of an applied…

Mesoscale and Nanoscale Physics · Physics 2020-07-01 Y. Li , M. Amado , T. Hyart , G. P. Mazur , V. Risinggård , T. Wagner , L. McKenzie Sell , G. Kimbell , J. Wunderlich , J. Linder , J. W. A. Robinson

We analyze the phase diagram of twisted graphene bilayers near a magic angle. We consider the effect of the long range Coulomb interaction, treated within the self consistent Hartree-Fock approximation, and we study arbitrary band fillings.…

Strongly Correlated Electrons · Physics 2020-07-15 Tommaso Cea , Francisco Guinea