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A semimagnetic topological insulator -- a heterostructure combining a topological insulator with a ferromagnet -- exhibits a half-quantized Hall effect, characterized by a quantized Hall conductance of $\frac{1}{2}\frac{e^{2}}{h}$ (where…

Disordered Systems and Neural Networks · Physics 2025-10-30 Shi-Hao Bi , Bo Fu , Shun-Qing Shen

The inverted band structure discovered in InAs/GaSb quantum well (QW) is found to host the topological quantum spin Hall (QSH) states. A QSH insulator hosts counterpropagating spin-polarized edge states that are protected by the…

Mesoscale and Nanoscale Physics · Physics 2022-08-30 Sushmita Saha , Alestin Mawrie

Ferromagnetic topological insulators in the quantum anomalous Hall (QAH) regime host chiral, dissipationless edge states whose propagation direction is determined by the internal magnetization. Under suitable conditions, a strong electrical…

Mesoscale and Nanoscale Physics · Physics 2025-07-29 Alina Rupp , Daniel Rosenbach , Torsten Röper , Dominik Hoborka , Alexey A. Taskin , Yoichi Ando , Erwann Bocquillon

Recent experimental progress in condensed matter physics enables the observation of signatures of the parity anomaly in two-dimensional Dirac-like materials. Using effective field theories and analyzing band structures in external…

Mesoscale and Nanoscale Physics · Physics 2020-08-13 J. Böttcher , C. Tutschku , L. W. Molenkamp , E. M. Hankiewicz

In a GaAs/AlGaAs two-dimensional electron system with two occupied subbands, the experimentally determined phase diagram in the density-magnetic field plane exhibits rich topological features. Ring-like structures are observed at even…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 X. C. Zhang , D. R. Faulhaber , H. W. Jiang

The effect of magnetic field on an ultrathin magnetic topological insulator film with structural inversion asymmetry is investigated. We introduce the phase diagram, calculate the Landau-level spectrum analytically and simulate the…

Mesoscale and Nanoscale Physics · Physics 2016-05-13 Shu-feng Zhang , Hua Jiang , X. C. Xie , Qing-feng Sun

The experimental observation of the long-sought quantum anomalous Hall effect was recently reported in magnetically doped topological insulator thin films [Chang et al., Science 340, 167 (2013)]. An intriguing observation is a rapid…

Mesoscale and Nanoscale Physics · Physics 2013-10-04 Hai-Zhou Lu , An Zhao , Shun-Qing Shen

The quantum Hall (QH) effect, quantized Hall resistance combined with zero longitudinal resistance, is the characteristic experimental fingerprint of Chern insulators - topologically non-trivial states of two-dimensional matter with broken…

Mesoscale and Nanoscale Physics · Physics 2023-02-07 Cui-Zu Chang , Chao-Xing Liu , Allan H. MacDonald

Quantum anomalous Hall insulators are topologically characterized by non-zero integer Chern numbers, the sign of which depends on the direction of the exchange field that breaks time-reversal symmetry. This feature allows the manipulation…

Mesoscale and Nanoscale Physics · Physics 2024-09-06 Nezhat Pournaghavi , Carlo M. Canali

The quantum anomalous Hall (QAH) effect holds fundamental importance in topological physics and technological promise for electronics. It is generally believed that the QAH effect can only be realized in insulators. In this Letter, we…

Mesoscale and Nanoscale Physics · Physics 2025-12-30 Yu-Hao Wan , Peng-Yi Liu , Qing-Feng Sun

The quantum anomalous Hall effect (QAHE) that emerges under broken time-reversal symmetry in topological insulators (TI) exhibits many fascinating physical properties for potential applications in nano-electronics and spintronics. However,…

We study the phase diagram of a model quantum spin Hall system as a function of band inversion and band-coupling strength, demonstrating that when band hybridization is weak, an interaction-induced nematic insulator state emerges over a…

Mesoscale and Nanoscale Physics · Physics 2018-05-09 Fei Xue , Allan H. MacDonald

A quantum phase transition arises from competition between different ground states and is typically accessed by varying a single physical parameter near absolute zero temperature. The quantum anomalous Hall (QAH) effect with high Chern…

Mesoscale and Nanoscale Physics · Physics 2025-08-27 Ling-Jie Zhou , Deyi Zhuo , Ruobing Mei , Yi-Fan Zhao , Kaijie Yang , Ruoxi Zhang , Zijie Yan , Han Tay , Moses H. W. Chan , Chao-Xing Liu , Cui-Zu Chang

We report results of numerical studies of the integer quantum Hall effect in a tight binding model on a two-dimensional square lattice with non-interacting electrons, in the presence of a random potential as well as a uniform magnetic field…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Kun Yang , R. N. Bhatt

We study theoretically the role of quenched magnetic disorder at the surface of a topological insulator by numerical simulation and scaling analysis. It is found that all the surface states are localized while the transverse conductivity is…

Mesoscale and Nanoscale Physics · Physics 2011-04-19 Kentaro Nomura , Naoto Nagaosa

Surface states of a topological insulator demonstrate interesting quantum phenomena, such as the quantum anomalous Hall (QAH) effect and the quantum magnetoelectric effect. Fermi energy tuning plays a role in inducing phase transitions and…

Mesoscale and Nanoscale Physics · Physics 2023-09-26 Ryota Watanabe , Ryutaro Yoshimi , Kei S. Takahashi , Atsushi Tsukazaki , Masashi Kawasaki , Minoru Kawamura , Yoshinori Tokura

Quasi-periodically driven quantum systems are predicted to exhibit quantized topological properties, in analogy with the quantized transport properties of topological insulators. We use a single nitrogen-vacancy center in diamond to…

Mesoscale and Nanoscale Physics · Physics 2020-10-21 Eric Boyers , Philip J. D. Crowley , Anushya Chandran , Alexander O. Sushkov

A general mechanism is presented by which topological physics arises in strongly correlated systems without flat bands. Starting from a charge transfer insulator, topology emerges when the charge transfer energy between the cation and anion…

Strongly Correlated Electrons · Physics 2022-09-08 Trithep Devakul , Liang Fu

The pursuit of understanding parity anomaly in condensed matter systems has led to significant advancements in both theoretical and experimental research in recent years. In this study, we explore the parity anomaly of massless Dirac…

Mesoscale and Nanoscale Physics · Physics 2024-03-14 Huan-Wen Wang , Bo Fu , Shun-Qing Shen

The quantum anomalous Hall effect (QAHE), the last member of Hall family, was predicted to exhibit quantized Hall conductivity e2/h without any external magnetic field. The QAHE shares a similar physical phenomenon with the integer quantum…

Mesoscale and Nanoscale Physics · Physics 2016-03-23 Cui-Zu Chang , Mingda Li