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Superconductivity and the quantum Hall effect are conventionally regarded as mutually exclusive: superconductivity is suppressed by magnetic fields, whereas the quantum Hall effect relies on them. Here we report a striking exception, where…

The quantum anomalous Hall effect (QAHE) is a fundamental quantum transport phenomenon that manifests as a quantized transverse conductance in response to a longitudinally applied electric field in the absence of an external magnetic field,…

Capacitance measurements provide a powerful means of probing the density of states. The technique has proved particularly successful in studying 2D electron systems, revealing a number of interesting many-body effects. Here, we use…

Graphene and its van der Waals (vdW) heterostructures provide a unique and versatile playground for explorations of strongly correlated electronic phases, ranging from unconventional fractional quantum Hall (FQH) states in a monolayer…

Mesoscale and Nanoscale Physics · Physics 2023-03-17 A. Popert , Y. Shimazaki , M. Kroner , K. Watanabe , T. Taniguchi , A. Imamoğlu , T. Smoleński

The quantum anomalous Hall effect (QAHE) is a robust topological phenomenon featuring quantized Hall resistance at zero magnetic field. We report the QAHE in a rhombohedral pentalayer graphene/monolayer WS2 heterostructure. Distinct from…

Mesoscale and Nanoscale Physics · Physics 2024-05-14 Tonghang Han , Zhengguang Lu , Yuxuan Yao , Jixiang Yang , Junseok Seo , Chiho Yoon , Kenji Watanabe , Takashi Taniguchi , Liang Fu , Fan Zhang , Long Ju

Graphene is a model system for the study of electrons confined to a strictly two-dimensional layer1 and a large number of electronic phenomena have been demonstrated in graphene, from the fractional2, 3 quantum Hall effect to…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 Jian-Hao Chen , W. G. Cullen , E. D. Williams , M. S. Fuhrer

The quantum Hall effect (QHE) theoretically provides a universal standard of electrical resistance in terms of the Planck constant $h$ and the electron charge $e$. In graphene, the spacing between the lowest discrete energy levels occupied…

Mesoscale and Nanoscale Physics · Physics 2015-04-27 R. Ribeiro-Palau , F. Lafont , J. Brun-Picard , D. Kazazis , A. Michon , F. Cheynis , O. Couturaud , C. Consejo , B. Jouault , W. Poirier , F. Schopfer

Recently unusual integer quantum Hall effect was observed in graphene in which the Hall conductivity is quantized as $\sigma_{xy}=(\pm 2, \pm 6, \pm 10, >...) \times \frac{e^2}{h}$, where $e$ is the electron charge and $h$ is the Planck…

Disordered Systems and Neural Networks · Physics 2007-05-23 Yasumasa Hasegawa , Mahito Kohmoto

We discuss the effect of electron-electron interactions on the static polarization properties of graphene beyond RPA. Divergent self-energy corrections are naturally absorbed into the renormalized coupling constant $\alpha$. We find that…

Strongly Correlated Electrons · Physics 2008-07-18 Valeri N. Kotov , Bruno Uchoa , A. H. Castro Neto

We show that the recently discovered double-valley splitting of the low-lying Landau level(s) in the Quantum Hall Effect in graphene can be explained as perturbative orbital interaction of intra- and inter-valley microscopic orbital…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Igor A. Luk'yanchuk , Alexander M. Bratkovsky

Starting from the graphene lattice tight-binding Hamiltonian with an on-site U and long-range Coulomb repulsion, we derive an interacting continuum Dirac theory governing the low-energy behavior of graphene in an applied magnetic field.…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Jason Alicea , Matthew P. A. Fisher

We have developed a device fabrication process to pattern graphene into nanostructures of arbitrary shape and control their electronic properties using local electrostatic gates. Electronic transport measurements have been used to…

Mesoscale and Nanoscale Physics · Physics 2008-04-14 Barbaros Özyilmaz , Pablo Jarillo-Herrero , Dmitri Efetov , Dmitri A. Abanin , Leonid S. Levitov , Philip Kim

The quantum Hall (QH) effect supports a set of chiral edge states at the boundary of a 2-dimensional electron gas (2DEG) system. A superconductor (SC) contacting these states induces correlation of the quasi-particles in the dissipationless…

Mesoscale and Nanoscale Physics · Physics 2017-05-12 Gil-Ho Lee , Ko-Fan Huang , Dmitri K. Efetov , Di S. Wei , Sean Hart , Takashi Taniguchi , Kenji Watanabe , Amir Yacoby , Philip Kim

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

The quantum Hall effect (QHE) in two-dimensional (2D) electron gases, which is one of the most striking phenomena in condensed matter physics, involves the topologically protected dissipationless charge current flow along the edges of the…

Strongly Correlated Electrons · Physics 2018-08-02 Y. Kasahara , T. Ohnishi , Y. Mizukami , O. Tanaka , Sixiao Ma , K. Sugii , N. Kurita , H. Tanaka , J. Nasu , Y. Motome , T. Shibauchi , Y. Matsuda

Low temperature magnetoconductance measurements were made in the vicinity of the charge neutrality point. Two origins for the fluctuations were identified close to the CNP. At very low magnetic fields there exist only mesoscopic…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Simon Branchaud , Alicia Kam , Piotr Zawadzki , Francois M. Peeters , Andrew S. Sachrajda

We consider graphene deposited on monolayers of such transition-metal dichalcogenides like MoSe$_2$, WSe$_2$, MoS$_2$, and WS$_2$. Our key objective is to study the impact of relative twist angle between the monolayers on the…

Mesoscale and Nanoscale Physics · Physics 2025-07-02 I. Wojciechowska , A. Dyrdal

We study the low-energy quantum electrodynamics of electrons and holes, in a thin graphene wire. We develop an effective field theory (EFT) based on an expansion in p/p_T, where p_T is the typical momentum of electrons and holes in the…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 P. Faccioli , E. Lipparini

We present measurements of quantized conductance in electrostatically induced quantum point contacts in bilayer graphene. The application of a perpendicular magnetic field leads to an intricate pattern of lifted and restored degeneracies…

In a Bernal-stacked graphene bilayer, an electronic state in Landau level $% N=0$ is described by its guiding-center index $X$ (in the Landau gauge) and by its valley, spin, and orbital indices $\xi =\pm K,\sigma =\pm 1,$ and $% n=0,1.$…

Mesoscale and Nanoscale Physics · Physics 2014-01-08 J. Lambert , R. Côté