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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

We report a twisted triple bilayer graphene platform consisting of three units of Bernal bilayer graphene consecutively twisted at 1.49{\deg} and 1.68{\deg}. We demonstrate the atomic reconstruction between the two competing moir\'e…

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

The emergence of the fascinating non-linear Hall effect intrinsically depends on the non-zero value of the Berry curvature dipole. In this work, we predict that suitable strain engineering in layered van der Waals material phosphorene can…

Mesoscale and Nanoscale Physics · Physics 2024-05-21 Arka Bandyopadhyay , Nesta Benno Joseph , Awadhesh Narayan

Berry phase plays an important role in determining many physical properties of quantum systems. However, a Berry phase altering energy spectrum of a quantum system is comparatively rare. Here, we report an unusual tunable valley polarized…

Mesoscale and Nanoscale Physics · Physics 2021-08-18 Ya-Ning Ren , Qiang Cheng , Qing-Feng Sun , Lin He

We study the anomalous Hall effect, magneto-optical properties, and nonlinear optical properties of twisted bilayer graphene (TBG) aligned with hexagonal boron nitride (hBN) substrate as well as twisted double bilayer graphene systems. We…

Mesoscale and Nanoscale Physics · Physics 2021-01-27 Jianpeng Liu , Xi Dai

The electronic dispersion of a graphene bilayer is highly dependent on rotational mismatch between layers and can be further manipulated by electrical gating. This allows for an unprecedented control over electronic properties and opens up…

Materials Science · Physics 2016-08-31 Johannes C. Rode , Dmitri Smirnov , Hennrik Schmidt , Rolf J. Haug

Recently, it has been pointed out that the twisting of bilayer WSe$_2$ would generate topologically non-trivial flat bands near the Fermi energy. In this work, we show that twisted bilayer WSe$_2$ (tWSe$_2$) with uniaxial strain exhibits a…

Mesoscale and Nanoscale Physics · Physics 2022-12-29 Jin-Xin Hu , Cheng-Ping Zhang , Ying-Ming Xie , K. T. Law

It is observed experimentally that the sign of the Hall resistance can be flipped by a dc electric current in the twisted bilayer graphene (TBG) at 3/4 filling of the four-fold degenerate conduction flat bands. The experiment implies a…

Strongly Correlated Electrons · Physics 2020-11-25 Ying Su , Shi-Zeng Lin

The Berry curvature in magnetic systems is attracting interest due to the potential tunability of topological features via the magnetic structure. $f$-electrons, with their large spin-orbit coupling, abundance of non-collinear magnetic…

Strongly Correlated Electrons · Physics 2020-07-29 T. Asaba , Ying Su , M. Janoschek , J. D. Thompson , S. M. Thomas , E. D. Bauer , Shi-Zeng Lin , F. Ronning

Valley polarized twisted bilayer dice lattice hosts topologically nontrivial flat bands far from charge neutrality due to broken time reversal symmetry, whereas the ones in the vicinity of it remain topologically trivial. However, when both…

Mesoscale and Nanoscale Physics · Physics 2026-05-21 Gourab Paul , Srijata Lahiri , Bilal Tanatar , Saurabh Basu

Valley Hall effect has been observed in asymmetric single-layer and bilayer graphene systems. In single-layer graphene systems, asymmetry is introduced by aligning graphene with hexagonal boron nitride (hBN) with a near-zero twist angle,…

Mesoscale and Nanoscale Physics · Physics 2023-11-16 Teppei Shintaku , Afsal Kareekunnan , Masashi Akabori , Kenji Watanabe , Takashi Taniguchi , Hiroshi Mizuta

We consider the anomalous thermoelectric transport in gapped single and bilayer graphene where the gap may be due to broken inversion symmetry. In the presence of the gap, non-trivial Berry phase effects can be shown to mediate a transverse…

Mesoscale and Nanoscale Physics · Physics 2009-07-21 Chuanwei Zhang , Sumanta Tewari , S. Das Sarma

High-order terahertz (THz) sideband generation (HSG) in semiconductors is a phenomenon with physics similar to high-order harmonic generation but in a much lower frequency regime. It was found that the electron-hole pairs excited by a weak…

Mesoscale and Nanoscale Physics · Physics 2014-04-17 Fan Yang , Xiaodong Xu , Ren-Bao Liu

We study the quantum nonlinear Hall effect in two-dimensional materials with time-reversal symmetry. When only one mirror line exists, a transverse charge current occurs in second-order response to an external electric field, as a result of…

Mesoscale and Nanoscale Physics · Physics 2018-10-03 Jhih-Shih You , Shiang Fang , Su-Yang Xu , Efthimios Kaxiras , Tony Low

The anomalous Hall effect describes the generation of a transverse voltage by a longitudinal current even in the absence of an external magnetic field. While typically observed in ferromagnets, it has also been predicted to arise in…

Recent experimental evidence for the quantum spin Hall (QSH) state in monolayer WTe$_2$ has bridged two of the most active fields of condensed matter physics, 2D materials and topological physics. This 2D topological crystal also displays…

In the presence of time reversal symmetry, a non-linear Hall effect can occur in systems without an inversion symmetry. One of the prominent candidates for detection of such Hall signals are Weyl semimetals. In this article, we investigate…

Mesoscale and Nanoscale Physics · Physics 2023-08-22 Saswata Roy , Awadhesh Narayan

The recent observed anomalous Hall effect in magic angle twisted bilayer graphene (TBG) aligned to hexagonal boron nitride (hBN) and unconventional ferroelectricity in Bernal bilayer graphene sandwiched by hBN present a new platform to tune…

Mesoscale and Nanoscale Physics · Physics 2024-02-01 Min Long , Zhen Zhan , Pierre A. Pantaleón , Jose Ángel Silva-Guillén , Francisco Guinea , Shengjun Yuan

Magnetic semimetals have increasingly emerged as lucrative platforms hosting spin-based topological phenomena in real and momentum spaces. Of particular interest is the emergence of Berry curvature, whose geometric origin, accessibility…