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In two-dimensional electronic lattices, changes in the topology of the Fermi surface (Lifshitz transitions) lead to Van Hove singularities characterized by a divergence in the electronic density of states. Van Hove singularities can enhance…

Mesoscale and Nanoscale Physics · Physics 2024-02-27 Lakshmi Pullasseri , Luiz H. Santos

We reveal a proximity effect between a topological band (Chern) insulator described by a Haldane model and spin-polarized Dirac particles of a graphene layer. Coupling weakly the two systems through a tunneling term in the bulk, the…

Mesoscale and Nanoscale Physics · Physics 2019-08-21 Peng Cheng , Philipp W. Klein , Kirill Plekhanov , Klaus Sengstock , Monika Aidelsburger , Christof Weitenberg , Karyn Le Hur

We consider the two-dimensional topological Chern insulator in the presence of static disorder. Generic quantum states in this system are Anderson localized. However, topology requires the presence of a subset of critical states, with…

Mesoscale and Nanoscale Physics · Physics 2023-08-29 Mateo Moreno-Gonzalez , Johannes Dieplinger , Alexander Altland

Using first principles methods, we investigate topological phase transitions as a function of exchange field in a Bi(111) bilayer. Evaluation of the spin Chern number for different magnitudes of the exchange field reveals that when the time…

Materials Science · Physics 2013-08-22 Hongbin Zhang , Frank Freimuth , Gustav Bihlmayer , Stefan Blügel , Yuriy Mokrousov

We discuss the Chern number spectrum of ultra-cold fermions in square optical lattices as a function of artificial magnetic, Zeeman and spin-orbit fields that can be tuned independently. We show the existence of topological quantum phase…

Quantum Gases · Physics 2019-05-01 Man Hon Yau , C. A. R. Sa de Melo

We show a tight-binding model for double perovskite monolayers grown in the {001} crystallographic direction can exhibit higher Chern numbers for the lowest band of the model dispersion in the absence of an applied magnetic field, including…

Strongly Correlated Electrons · Physics 2016-11-28 A. M. Cook

We present a complete topological characterization of a bilayer composite of two Chern insulators (specifically, Haldane models) and explicitly establish the bulk-boundary correspondences. We show that an appropriately defined Chern number…

Statistical Mechanics · Physics 2021-06-15 Sourav Bhattacharjee , Souvik Bandyopadhyay , Diptiman Sen , Amit Dutta

We study the possibility of realizing quantum anomalous Hall effect (QAHE) with tunable Chern number through doping magnetic elements in the multi-layer topological insulator film. We find that high Chern number QAHE phases exist in the…

Mesoscale and Nanoscale Physics · Physics 2013-05-30 Hua Jiang , Zhenhua Qiao , Haiwen Liu , Qian Niu

The recent observation of the fractional quantum anomalous Hall effect in moir\'e fractional Chern insulators provides an opportunity to investigate zero magnetic field anyons. To potentially realize non-Abelian anyons, one approach is to…

Magnetic topological insulators (TIs) provide a highly tunable platform for engineering quantum states that emerge from the interplay between topology and magnetism. In this review article, we summarize experimental progress over the past…

Mesoscale and Nanoscale Physics · Physics 2026-05-21 Deyi Zhuo , Han Tay , Cui-Zu Chang

Twisting two layers into a magic angle (MA) of ~1.1{\deg} is found essential to create low energy flat bands and the resulting correlated insulating, superconducting, and magnetic phases in twisted bilayer graphene (TBG). While most of…

The classification of bandstructures by topological invariants provides a powerful tool for understanding phenomena such as the quantum Hall effect. This classification was originally developed in the context of electrons, but can also be…

Optics · Physics 2020-09-14 R. L. Mc Guinness , P. R. Eastham

We analyze the influence of disorder and strong correlations on the topology in two dimensional Chern insulators. A mean field calculation in the half-filled Haldane model with extended Hubbard interactions and Anderson disorder shows that…

Strongly Correlated Electrons · Physics 2024-09-19 Joao S. Silva , Eduardo V. Castro , Rubem Mondaini , María A. H. Vozmediano , M. Pilar López-Sancho

Manipulating the topological properties of insulators, encoded in invariants such as the Chern number and its generalizations, is now a major issue for realizing novel charge/spin responses in electron systems. We propose that a simple…

Materials Science · Physics 2010-06-30 Jun-ichi Inoue , Akihiro Tanaka

When translational symmetry is broken by bulk disorder, the topological nature of states in topological crystalline systems may change depending on the type of disorder that is applied. In this work, we characterize the phases of a…

Strongly Correlated Electrons · Physics 2021-02-01 Saavanth Velury , Barry Bradlyn , Taylor L. Hughes

We study translationally-invariant insulators with inversion symmetry that fall outside the established classification of topological insulators. These insulators are not required to have gapless boundary modes in the energy spectrum.…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 Taylor L. Hughes , Emil Prodan , B. Andrei Bernevig

Based on the full Hamiltonian of bilayer graphene, phase transitions are realized by the change of the in-plane magnetic field and the electrical bias in bilayer graphene. We show that the engineering of Chern numbers of four bands is…

Mesoscale and Nanoscale Physics · Physics 2024-05-24 Narjes Kheirabadi

Recently, it has been shown how topological phases of matter with crystalline symmetry and $U(1)$ charge conservation can be partially characterized by a set of many-body invariants, the discrete shift $\mathscr{S}_{\text{o}}$ and electric…

Strongly Correlated Electrons · Physics 2025-02-28 Yuxuan Zhang , Maissam Barkeshli

The search for candidate materials for fractional Chern insulators (FCIs) has mainly focused on the topological and geometrical structures of single-particle Chern bands. However, there are inherent limitations in approaches that neglect…

Strongly Correlated Electrons · Physics 2025-12-29 Nobuyuki Okuma , Tomonari Mizoguchi

We report the theoretical discovery of a systematic scheme to produce topological flat bands (TFBs) with arbitrary Chern numbers. We find that generically a multi-orbital high Chern number TFB model can be constructed by considering…

Strongly Correlated Electrons · Physics 2013-01-01 Shuo Yang , Zheng-Cheng Gu , Kai Sun , S. Das Sarma