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The electronic topology is generally related to the Berry curvature, which can induce the anomalous Hall effect in time-reversal symmetry breaking systems. Intrinsic monolayer transition metal dichalcogenides possesses two nonequivalent K…

Mesoscale and Nanoscale Physics · Physics 2021-07-07 Mao-Sen Qin , Peng-Fei Zhu , Xing-Guo Ye , Wen-Zheng Xu , Zhen-Hao Song , Jing Liang , Kaihui Liu , Zhi-Min Liao

In the recent years, there has been a drive towards the realization of topological phases beyond conventional electronic materials, including phases defined in more than three dimensions. We propose a way to realize 2nd Chern number…

Mesoscale and Nanoscale Physics · Physics 2017-12-14 Xiao Zhang , You Jian Chen , Bochen Guan , Jun Yu Lin , Nai Chao Hu , Ching Hua Lee

Here we study the systematic evolution of the topological properties of a Chern insulator in presence of an electronic dispersion that can be tuned smoothly from being Dirac-like till a semi-Dirac one and beyond. The band structure under…

Mesoscale and Nanoscale Physics · Physics 2022-03-31 Sayan Mondal , Priyadarshini Kapri , Bashab Dey , Tarun Kanti Ghosh , Saurabh Basu

Helical twisted trilayer graphene exhibits zero-energy flat bands with large degeneracy in the chiral limit. The flat bands emerge at a discrete set of magic twist angles and feature properties intrinsically distinct from those realized in…

Mesoscale and Nanoscale Physics · Physics 2023-08-08 Daniele Guerci , Yuncheng Mao , Christophe Mora

We predict twisted double bilayer graphene to be a versatile platform for the realization of fractional Chern insulators readily targeted by tuning the gate potential and the twist angle. Remarkably, these topologically ordered states of…

Mesoscale and Nanoscale Physics · Physics 2021-01-18 Zhao Liu , Ahmed Abouelkomsan , Emil J. Bergholtz

The valley Chern-effect is theoretically demonstrated with a novel alternating current circuitry, where closed-loop LC-resonators sitting at the nodes of a honeycomb lattice are inductively coupled along the bonds. This enables us to…

Mesoscale and Nanoscale Physics · Physics 2019-05-01 Yishai Eisenberg , Yafis Barlas , Emil Prodan

The semiclassical quantization of cyclotron orbits for two-dimensional Bloch electrons in a coupled two band model with a particle-hole symmetric spectrum is considered. As concrete examples, we study graphene (both mono and bilayer) and…

Mesoscale and Nanoscale Physics · Physics 2015-05-19 J. N. Fuchs , F. Piechon , M. O. Goerbig , G. Montambaux

We study the electronic structure of alternating-twist tetralayer graphene, especially near its magic angle $\theta = 1.75^\circ$, for different AA, AB, and SP sliding geometries at their middle interface that divides two twisted bilayer…

Mesoscale and Nanoscale Physics · Physics 2024-09-30 Kyungjin Shin , Jiseon Shin , Yoonsung Lee , Hongki Min , Jeil Jung

Electronic band structures dictate the mechanical, optical and electrical properties of crystalline solids. Their experimental determination is therefore of crucial importance for technological applications. While the spectral distribution…

Mesoscale and Nanoscale Physics · Physics 2019-10-02 C. Dutreix , H. González-Herrero , I. Brihuega , M. I. Katsnelson , C. Chapelier , V. T. Renard

The quantum anomalous Hall (QAH) insulator is uniquely characterized by the topological Chern number C. Controlling the Chern number is a key step toward functional topological electronics and enables access to exotic quantum phases beyond…

Thin film of superfluid $^3$He on a corrugated graphene substrate represents topological matter with a smooth disorder. It is possible that the atomically smooth disorder produced by the corrugated graphene does not destroy the…

Strongly Correlated Electrons · Physics 2019-09-04 G. E. Volovik

We argue that ferromagnetic transition metal nanoparticles with fewer than approximately 100 atoms can be described by an effective Hamiltonian with a single giant spin degree of freedom. The total spin $S$ of the effective Hamiltonian is…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 C. M. Canali , A. Cehovin , A. H. MacDonald

We propose a Haldane-like model of dice lattice analogous to graphene and explore its topological properties within the tight-binding formalism. The topological phase boundary of the system is identical to that of Haldane model of graphene…

Mesoscale and Nanoscale Physics · Physics 2020-06-04 Bashab Dey , Priyadarshini Kapri , Ojasvi Pal , Tarun Kanti Ghosh

A valley-contrasting Berry curvature in bilayer transition metal dichalcogenides with spin-orbit coupling can generate valley magnetization when the inversion symmetry is broken, for example, by an electric field, regardless of…

Mesoscale and Nanoscale Physics · Physics 2021-01-12 Vassilios Vargiamidis , P. Vasilopoulos , M. Tahir , Neophytos Neophytou

We derive a general relation between the stacking vector ${\bf u}$ describing the relative shift of two layers of bilayer graphene and the Chern index. We find $C = \nu - \text{sign}\left(|V_{AB}|-|V_{BA}|\right)$, where $\nu$ is a valley…

Mesoscale and Nanoscale Physics · Physics 2021-09-22 S. Theil , M. Fleischmann , R. Gupta , F. Wullschläger , S. Sharma , B. Meyer , S. Shallcross

Rhombohedral multilayer graphene has emerged as a powerful platform for investigating flat-band-driven correlated phenomena, yet most aspects remain not understood. In this work, we systematically study the moire-dependent band topology in…

If an extensive partition in two dimensions yields a gapful entanglement spectrum of the reduced density matrix, the Berry curvature based on the corresponding entanglement eigenfunction defines the Chern number. We propose such an…

Mesoscale and Nanoscale Physics · Physics 2014-10-15 T. Fukui , Y. Hatsugai

The quantum level interplay between geometry, topology, and correlation is at the forefront of fundamental physics. Owing to the unusual lattice geometry and breaking of time-reversal symmetry, kagome magnets are predicted to support…

When electrons are confined in two-dimensional (2D) materials, quantum mechanically enhanced transport phenomena, as exemplified by the quantum Hall effects (QHE), can be observed. Graphene, an isolated single atomic layer of graphite, is…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Yuanbo Zhang , Yan-Wen Tan , Horst L. Stormer , Philip Kim

The realization of fractional Chern insulators opens up the possibility of exploring fractionally charged excitations and anyonic statistics in the absence of a magnetic field. One of the central questions is whether lattice-based systems…

Mesoscale and Nanoscale Physics · Physics 2025-12-29 Zexu Li , Wenxuan Wang , Fajie Wang , Zaizhe Zhang , Qiu Yang , Kenji Watanabe , Takashi Taniguchi , X. C. Xie , Jie Wang , Kaihui Liu , Zhida Song , Xiaobo Lu