Article
Materials Science, Multidisciplinary
Dawei Kang, Zhaowu Wang, Zheng-wei Zuo
Summary: In this work, multiple flat bands with extremely low bandwidth were discovered in twisted bilayer binary materials at large twist angles. Atomic reconstruction plays a crucial role in the formation of these ultraflat bands.
Article
Chemistry, Multidisciplinary
Ding Pei, Zishu Zhou, Zhihai He, Liheng An, Han Gao, Hanbo Xiao, Cheng Chen, Shanmei He, Alexei Barinov, Jianpeng Liu, Hongming Weng, Ning Wang, Zhongkai Liu, Yulin Chen
Summary: The recent discovery of strongly correlated phases in twisted transition metal dichalcogenides (TMDs) highlights the significant impact of twist-induced modifications on electronic structures. In this study, angle-resolved photoemission spectroscopy with submicrometer spatial resolution (mu-ARPES) was used to investigate these modifications by comparing valence band structures of twisted and nontwisted bilayer regions within the same WSe2 device. The results show the presence of pronounced moire bands, a substantial momentum separation between different layers, and an absence of flat bands in the twisted area, indicating twist-induced modifications in the electronic structures of TMDs.
Article
Physics, Multidisciplinary
G. Gatti, J. Issing, L. Rademaker, F. Margot, T. A. De Jong, S. J. van der Molen, J. Teyssier, T. K. Kim, M. D. Watson, C. Cacho, P. Dudin, J. Avila, K. Cordero Edwards, P. Paruch, N. Ubrig, I. Gutierrez-Lezama, A. F. Morpurgo, A. Tamai, F. Baumberger
Summary: Researchers used real- and momentum-space mapping techniques to study moire superlattice effects in twisted WSe2, revealing a split-off flat band from monolayer Γ states and quantifying the moire potential directly. They demonstrated that the global valence band maximum and the flat band derived from monolayer K states are close in energy, but with weaker superlattice effects. These findings constrain theoretical models and suggest the involvement of Γ-valley flat bands in the correlated physics of twisted WSe2.
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Shengdan Tao, Xuanlin Zhang, Jiaojiao Zhu, Pimo He, Shengyuan A. Yang, Yunhao Lu, Su-Huai Wei
Summary: A new design principle is proposed to achieve low-energy ultra-flat bands with increased twist angles in intertwined bilayers of two-dimensional materials, providing a new route for investigating strong electron correlations.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Materials Science, Multidisciplinary
Jiseon Shin, Bheema Lingam Chittari, Yunsu Jang, Hongki Min, Jeil Jung
Summary: In this study, we investigate the electronic structure of alternating-twist triple Bernal-stacked bilayer graphene (t3BG) by varying interlayer coupling, twist angle, interlayer potential difference, and sliding vector. We find that under certain parameters, the bands can flatten down to low energy levels, facilitating the formation of correlation-driven gaps.
Article
Materials Science, Multidisciplinary
Sudipta Kundu, Mit H. Naik, H. R. Krishnamurthy, Manish Jain
Summary: We study the influence of strong spin-orbit interaction on the formation of flat bands in relaxed twisted bilayer WSe2. Flat bands emerge at twist angles near 0 degrees and 60 degrees, with the electronic structure being determined by interlayer hybridization and a moire potential for angles near 0 degrees, and by atomic rearrangements in the individual layers for angles near 60 degrees. Our findings match well with recent experimental observations.
Article
Nanoscience & Nanotechnology
Yang Xu, Kaifei Kang, Kenji Watanabe, Takashi Taniguchi, Kin Fai Mak, Jie Shan
Summary: Twisting the AB-homobilayer of WSe2 enables the realization of bilayer Hubbard model in the weak interlayer hopping limit, leading to observation of competing electronic states transition.
NATURE NANOTECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Arpit Arora, Jian Feng Kong, Justin C. W. Song
Summary: The study reveals that large injection currents can be generated in strained twisted bilayer graphene heterostructures under circularly polarized irradiation, showing significant responses in the THz regime. These injection currents serve as a useful probe for symmetry breaking in twisted bilayer graphene heterostructures and highlight the potential of twisted bilayer graphene in THz technology.
Article
Chemistry, Physical
Shuang Wu, Zhenyuan Zhang, K. Watanabe, T. Taniguchi, Eva Y. Andrei
Summary: In magic-angle twisted bilayer graphene, doping-induced Lifshitz transitions and van Hove singularities lead to the emergence of correlation-induced gaps and topologically non-trivial subbands. With the presence of a magnetic field, quantized Hall plateaus reveal the subband topology and signal the emergence of Chern insulators with Chern numbers. Additionally, a van Hove singularity at a filling of 3.5 suggests the possibility of a fractional Chern insulator, accompanied by a crossover from low-temperature metallic to high-temperature insulating behavior.
Article
Physics, Multidisciplinary
Yan Wang, Gui-qiang Yu, Guo-yu Luo, Zhi-qiang Li
Summary: This study presents systematic calculations on the electronic band structures and topological properties of twisted bilayer WSe2 under different external stimuli. It is found that extremely narrow bandwidth can be obtained for the top valence bands with small strain, and this strain-induced flat band provides a stable 2D system for studying electron strong correlation. The band gaps between the top valence bands increase significantly under pressure and vertical electric field, and vertical electric field can lead to topological transitions for the flat bands.
Article
Multidisciplinary Sciences
Peter Rickhaus, Folkert K. de Vries, Jihang Zhu, Elias Portoles, Giulia Zheng, Michele Masseroni, Annika Kurzmann, Takashi Taniguchi, Kenji Watanabe, Allan H. MacDonald, Thomas Ihn, Klaus Ensslin
Summary: This study discovered a correlated electron-hole state in double-bilayer graphene twisted to 2.37 degrees, where moire states retain much of their isolated bilayer character. This allows the generation of an energetic overlap between narrow isolated electron and hole bands with good nesting properties, leading to the formation of ordered states with reconstructed Fermi surfaces consistent with a density-wave state that can be tuned without introducing chemical dopants.
Article
Multidisciplinary Sciences
Meizhen Huang, Zefei Wu, Jinxin Hu, Xiangbin Cai, En Li, Liheng An, Xuemeng Feng, Ziqing Ye, Nian Lin, Kam Tuen Law, Ning Wang
Summary: This study reports a significant breakthrough in the efficiency of nonlinear Hall generation in small-angle-twisted bilayer WSe2, reaching 1000 V-1, which is a hundred times higher than the previous records. The researchers explained this result through the correlation-induced continuous Mott transition effect.
NATIONAL SCIENCE REVIEW
(2023)
Article
Chemistry, Physical
Ruiheng Su, Manabendra Kuiri, Kenji Watanabe, Takashi Taniguchi, Joshua Folk
Summary: Identifying the essential components of superconductivity in graphene-based systems remains a critical problem in two-dimensional materials research. This field is connected to the mysteries that underpin investigations of unconventional superconductivity in condensed-matter physics. Here we report the discovery of superconductivity in twisted double bilayer graphene (TDBG) in proximity to WSe2, showing the correlation between a high density of states and the emergence of superconductivity in TDBG while revealing a possible role for isospin fluctuations in the pairing.
Article
Multidisciplinary Sciences
Tianye Huang, Xuecou Tu, Changqing Shen, Binjie Zheng, Junzhuan Wang, Hao Wang, Kaveh Khaliji, Sang Hyun Park, Zhiyong Liu, Teng Yang, Zhidong Zhang, Lei Shao, Xuesong Li, Tony Low, Yi Shi, Xiaomu Wang
Summary: This study reports the direct observation of two new plasmon modes in macroscopic twisted bilayer graphene (tBLG) with a highly ordered moiré superlattice. These modes include chiral plasmons arising from the uncompensated Berry flux of the electron gas under optical pumping, and slow plasmonic modes resulting from interband transitions in AB-stacked domains. These findings are important for understanding the electromagnetic dynamics of small-angle tBLG and enabling strong light-matter interactions in the mid-wave infrared spectral window.
Article
Chemistry, Physical
Nathanael P. Kazmierczak, Madeline Van Winkle, Colin Ophus, Karen C. Bustillo, Stephen Carr, Hamish G. Brown, Jim Ciston, Takashi Taniguchi, Kenji Watanabe, D. Kwabena Bediako
Summary: Twisted bilayer graphene exhibits two-regime reconstruction mechanics based on twist angle, with applied heterostrain accumulating anisotropically in saddle-point regions to generate distinctive striped strain phases. Nanoscale spatial fluctuations in twist angle and uniaxial heterostrain were statistically evaluated, revealing the prevalence of short-range disorder in moire heterostructures. This study provides insights into the twist-angle-dependent electronic behavior and structural relaxation, disorder, and strain in moire materials.
Article
Physics, Applied
Benjamin T. Zhou, Cheng-Ping Zhang, K. T. Law
PHYSICAL REVIEW APPLIED
(2020)
Article
Physics, Multidisciplinary
Peng Fan, Rui-Zi Zhang, Jing Qi, En Li, Guo-Jian Qian, Hui Chen, Dong-Fei Wang, Qi Zheng, Qin Wang, Xiao Lin, Yu-Yang Zhang, Shixuan Du, W. A. Hofer, Hong-Jun Gao
Article
Physics, Multidisciplinary
Peng Fan, Guojian Qian, Dongfei Wang, En Li, Qin Wang, Hui Chen, Xiao Lin, Hong-Jun Gao
Summary: The study using STM/STS revealed the detailed electronic structures around the sharp edges and strained terraces of lateral monolayer-bilayer Pd2Se3 heterostructures, showing well-defined zigzag edges and band bending with alignment. The results provide effective toolsets to tune the band structures in Pd2Se3-based heterostructures and devices.
Article
Chemistry, Physical
Muqing Hua, Bowen Xia, Miao Wang, En Li, Jing Liu, Tianhao Wu, Yifan Wang, Ruoning Li, Honghe Ding, Jun Hu, Yongfeng Wang, Junfa Zhu, Hu Xu, Wei Zhao, Nian Lin
Summary: The study demonstrates the design and synthesis of a single-layer two-dimensional metal-organic framework containing a Kagome lattice of Fe(II) ions on a gold surface, with Fe(II) ions shown to be in a high spin state and exhibiting various degenerated spin configurations. Remarkably, a spin excitation at 6 meV was observed, pointing towards a possible route to realize a spin 1/2 Kagome antiferromagnetic system by replacing Fe(II) with Cu(II) in the same structure.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Physics, Multidisciplinary
Wen-Yu He, Xiao Yan Xu, K. T. Law
Summary: Kramers-Weyl semimetals, with a chiral crystal structure, exhibit a strong longitudinal magnetoelectric response, making them potential candidates for magnetic switching in ferromagnetic systems. This unique material property arises from the chiral lattice symmetry, allowing for new designs of spin-orbit torque devices with electric control of magnetization switching.
COMMUNICATIONS PHYSICS
(2021)
Article
Multidisciplinary Sciences
Ying-Ming Xie, Xue-Jian Gao, Xiao Yan Xu, Cheng-Ping Zhang, Jin-Xin Hu, Jason Z. Gao, K. T. Law
Summary: Recent research suggests that all chiral crystals with spin-orbit coupling can be Kramers Weyl semimetals, while all achiral non-centrosymmetric materials with spin-orbit coupling may be a new class of topological materials known as Kramers nodal line metals. These materials exhibit doubly degenerate lines connecting time-reversal invariant momenta, resulting in two types of Fermi surfaces.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Multidisciplinary
Ying-Ming Xie, Cheng-Ping Zhang, Jin-Xin Hu, Kin Fai Mak, K. T. Law
Summary: Moire heterobilayer transition metal dichalcogenides (TMDs) are ideal for simulating the single-band Hubbard model and interesting correlated phases have been observed in these systems. Recent research has shown that topologically nontrivial states can be observed in heterobilayers, in which pseudomagnetic fields induced by lattice relaxation play a crucial role.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Cheng-Kun Lyu, Yi-Fan Gao, Zi-Ang Gao, Song-Yu Mo, Mu-Qing Hua, En Li, Shu-Qing Fu, Jia-Yan Chen, Pei-Nian Liu, Li Huang, Nian Lin
Summary: In this study, single-layer two-dimensional cMOFs were successfully synthesized using on-surface synthesis method, consisting of HAT molecules and metal atoms. The magnetic moments of different metal atoms were found to vary, which may be attributed to the conjugated core and coordination properties of HAT.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Multidisciplinary Sciences
Yi Wan, En Li, Zhihao Yu, Jing-Kai Huang, Ming-Yang Li, Ang-Sheng Chou, Yi-Te Lee, Chien-Ju Lee, Hung-Chang Hsu, Qin Zhan, Areej Aljarb, Jui-Han Fu, Shao-Pin Chiu, Xinran Wang, Juhn-Jong Lin, Ya-Ping Chiu, Wen-Hao Chang, Han Wang, Yumeng Shi, Nian Lin, Yingchun Cheng, Vincent Tung, Lain-Jong Li
Summary: Two-dimensional semiconducting monolayers, such as transition metal dichalcogenides (TMDs), have great potential as channel materials in advanced electronics. Innovative growth reactions using hydroxide W species as a metal precursor show significantly lower defect density compared to conventional chemical vapor deposition (CVD) methods. Field-effect transistor (FET) devices based on this growth method exhibit high electron mobility and on-state current, comparable to exfoliated flakes, indicating the industrial potential of 2D materials.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
En Li, Cheng-Kun Lyu, Chengyi Chen, Huilin Xie, Jianyu Zhang, Jacky Wing Yip Lam, Ben Zhong Tang, Nian Lin
Summary: Creating conjugated macrocycles with unique chemical and physical properties is of great interest for functional supramolecular materials. In this study, we synthesized four-, six- and eight-membered TPE-based macrocycles on a surface, which self-assembled into two-dimensional supramolecular crystals. This work provides new insights into the photophysical properties of TPE-based macrocycles.
COMMUNICATIONS CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Xiao-Bo Wang, Bowen Xia, Cheng-Kun Lyu, Dongwook Kim, En Li, Shu-Qing Fu, Jia-Yan Chen, Pei-Nian Liu, Feng Liu, Nian Lin
Summary: The experimental realization of p-orbital honeycomb-Kagome lattice in a two dimensional metal-organic framework on a Au(111) substrate is achieved by combining two sublattices composed of molecules with p-orbital characteristics. It is demonstrated that p-orbital lattice can be realized in metal-organic frameworks by using molecules with molecular orbitals of p-orbital like symmetry.
COMMUNICATIONS CHEMISTRY
(2023)
Article
Physics, Multidisciplinary
Ying-Ming Xie, K. T. Law, Patrick A. Lee
Summary: The recent study discovered signatures of Majorana bound states in EuS/Au/superconductor heterostructures, with the formation mechanism explained using topological phase diagrams and scattering matrix methods. Chemical potential step and normal reflections are key factors for creating topological regimes, which exhibit periodic oscillations in size with variations in chemical potential and sample width. The ferromagnetic strip geometry is shown to have several advantages over other proposed quasi-one-dimensional schemes.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Physics, Multidisciplinary
Wen-Yu He, K. T. Law
Summary: In this study, it was found that the current-induced orbital magnetoelectric effect in superconductors can induce significant orbital magnetization, with a noticeable change near the superconductor-normal metal phase transition. The proposed theory can be useful for detecting unconventional magnetoelectric effects in superconductors with nonuniform pairing, such as twisted bilayer graphene.
PHYSICAL REVIEW RESEARCH
(2021)
