Article
Multidisciplinary Sciences
Xingdan Sun, Shihao Zhang, Zhiyong Liu, Honglei Zhu, Jinqiang Huang, Kai Yuan, Zhenhua Wang, Kenji Watanabe, Takashi Taniguchi, Xiaoxi Li, Mengjian Zhu, Jinhai Mao, Teng Yang, Jun Kang, Jianpeng Liu, Yu Ye, Zheng Vitto Han, Zhidong Zhang
Summary: The formation of interfacial moire superlattices in van der Waals vertical assemblies reconstructs crystal symmetry and provides opportunities for investigating exotic quantum states. The alignment of graphene monolayer to both top and bottom encapsulating hexagonal boron nitride leads to observed conductivity minima and correlated insulating states in a weak-interaction regime. The alignment of three 2D nanosheets leads to the formation of super-moire atomic lattices, influencing the electronic properties of van der Waals structures.
NATURE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Yajuan Cheng, Zheyong Fan, Tao Zhang, Masahiro Nomura, Sebastian Volz, Guimei Zhu, Baowen Li, Shiyun Xiong
Summary: We report a local minimum in thermal conductivity in twisted bilayer graphene (TBG) at the angle of 1.08 degrees, which corresponds to the 'magic angle' in the transition of several other reported properties. The thermal magic angle arises from the competition between the delocalization of atomic vibrational amplitudes and stresses on one hand, and the increased AA stacking density on the other hand. The manifestation of a magic angle, disclosing new thermal mechanisms at nanoscale, further uncovers the unique physics of two-dimensional materials.
MATERIALS TODAY PHYSICS
(2023)
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
Multidisciplinary Sciences
Yuan Hou, Zhaohe Dai, Shuai Zhang, Shizhe Feng, Guorui Wang, Luqi Liu, Zhiping Xu, Qunyang Li, Zhong Zhang
Summary: This study demonstrates that nanopockets in vdW materials can coalesce spontaneously into larger spaces which can be easily cleaned through mechanical methods, and that bilayer graphene interfaces exhibit excellent self-renewal phenomena in terms of moire patterns recovery after motion of contaminants.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Multidisciplinary
Junxi Duan, Yu Jian, Yang Gao, Huimin Peng, Jinrui Zhong, Qi Feng, Jinhai Mao, Yugui Yao
Summary: In the study, a giant second-order nonlinear Hall effect dominated by disorder-induced skew scattering was observed in twisted bilayer graphene. The magnitude and direction of the nonlinearity could be effectively tuned by gate voltage, and was mainly determined by the collaboration of static and dynamic disorders.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Dumitru Calugaru, Nicolas Regnault, Myungchul Oh, Kevin P. Nuckolls, Dillon Wong, Ryan L. Lee, Ali Yazdani, Oskar Vafek, B. Andrei Bernevig
Summary: This article analytically computes the scanning tunneling microscopy (STM) signatures of integer-filled correlated ground states of the magic angle twisted bilayer graphene (TBG) narrow bands and assesses the possibility of Kekule distortion (KD). The results show that coupling the two opposite graphene valleys does not always result in KD.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Pawel Potasz, Ming Xie, A. H. MacDonald
Summary: This study reports on finite-size exact-diagonalization calculations in a Hilbert space defined by the continuum-model flat moire bands of magic angle twisted bilayer graphene, showing evidence of a spin ferromagnet ground state for moire band filling between 3 and 2, and Chern insulator ground states with spontaneous spin, valley, and sublattice polarization near filling 3. It is emphasized that the inclusion of remote band self-energy is crucial for a reliable description of flat band correlations in magic angle twisted bilayer graphene.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Ipsita Mandal, Jia Yao, Erich J. Mueller
Summary: Experiments have shown that insulating behavior emerges in graphene bilayers when the moire bands are partially filled and the top layer is rotated relative to the bottom layer. By calculating charge distributions and estimating excitation gaps, researchers are able to further understand the properties of these phases.
Article
Nanoscience & Nanotechnology
Tomasz Chwiej
Summary: Twisted bilayer graphene exhibits low-energy relativistic gapless dispersion relation and can have transitory states with specific density superstructures.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2022)
Article
Physics, Multidisciplinary
Wen-Xuan Qiu, Bohao Li, Xun-Jiang Luo, Fengcheng Wu
Summary: Twisted bilayer MoTe2 is studied theoretically to predict its interaction-driven quantum phase diagrams and examine the dependence of phase boundaries on model parameters. These results provide guidance for the search for topological phases in twisted transition metal dichalcogenide homobilayers.
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
Multidisciplinary Sciences
En Li, Jin-Xin Hu, Xuemeng Feng, Zishu Zhou, Liheng An, Kam Tuen Law, Ning Wang, Nian Lin
Summary: The authors demonstrate the emergence of multiple ultra-flat electronic bands in twisted bilayer WSe2 using scanning tunneling microscopy and spectroscopy, indicating the potential for further study of exotic correlated phases in TB-TMDs.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Condensed Matter
Tomasz Chwiej
Summary: The large lattice constant of Moire superlattice in twisted bilayer graphene allows for the observation of Landau levels splitting into Hofstadter butterflies. The question of its robustness against spatial potential fluctuations is still being debated. By studying the energy structure of the twisted bilayer system under both homogeneous magnetic field and bias voltage, it is found that Landau levels are still formed despite the broken translational symmetry.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Multidisciplinary Sciences
Manabendra Kuiri, Christopher Coleman, Zhenxiang Gao, Aswin Vishnuradhan, Kenji Watanabe, Takashi Taniguchi, Jihang Zhu, Allan H. MacDonald, Joshua Folk
Summary: This study discovered a strong anomalous Hall effect in twisted double bilayer graphene, suggesting the breaking of time reversal symmetry due to orbital ferromagnetism. Gate voltages applied to the device can tune both the flatness and topology of the electronic bands, providing an unusual level of experimental control.
NATURE COMMUNICATIONS
(2022)
Article
Optics
Hongfei Wang, Shaojie Ma, Shuang Zhang, Dangyuan Lei
Summary: By considering continuous lattice dislocation, we discovered a class of superflat bands that can achieve continuously tunable superflat bands and corresponding localized states in general twisted bilayer systems.
LIGHT-SCIENCE & APPLICATIONS
(2022)
Article
Physics, Multidisciplinary
Bosong Sun, Wenjin Zhao, Tauno Palomaki, Zaiyao Fei, Elliott Runburg, Paul Malinowski, Xiong Huang, John Cenker, Yong-Tao Cui, Jiun-Haw Chu, Xiaodong Xu, S. Samaneh Ataei, Daniele Varsano, Maurizia Palummo, Elisa Molinari, Massimo Rontani, David H. Cobden
Summary: Evidence shows that monolayer WTe2 contains excitons formed by electrons and holes bound by Coulomb attraction, exhibiting V-shaped dependence on electrostatic doping and step in chemical potential at the neutral point upon cooling. Strong electronic interactions allow excitons to form and condense at high temperature, showing strong correlations over a wide temperature range.
Article
Materials Science, Multidisciplinary
Chen Chen, Li He, Chengxin Jiang, Lingxiu Chen, Hui Shan Wang, Xiujun Wang, Ziqiang Kong, Xiaojing Mu, Zhipeng Wei, Kenji Watanabe, Takashi Taniguchi, Tianru Wu, Daoli Zhang, Haomin Wang
Summary: This study investigates the directional etching of transition metal nanoparticles on the surface of hBN to produce nano-trenches with sharp edges. The orientation and shape of the trenches depend on the type of transition metal used, while the density and width of the trenches are affected by the etching temperature and solution concentration.
Article
Multidisciplinary Sciences
Jiaqi Cai, Dmitry Ovchinnikov, Zaiyao Fei, Minhao He, Tiancheng Song, Zhong Lin, Chong Wang, David Cobden, Jiun-Haw Chu, Yong-Tao Cui, Cui-Zu Chang, Di Xiao, Jiaqiang Yan, Xiaodong Xu
Summary: The authors realize a canted-antiferromagnetic Chern insulator in atomically-thin MnBi2Te4 with electrical control of chiral-edge state transport.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Anh N. Hong, Diana Luong, Mohammed Alghamdi, Wei-Cheng Liao, Weiyi Zhang, Emily Kusumoputro, Yichong Chen, P. Alex Greaney, Yongtao Cui, Jing Shi, Xianhui Bu, Boniface P. T. Fokwa, Pingyun Feng
Summary: Two new rod-packing metal-organic frameworks (RPMOF) were constructed by regulating the in situ formation of the capping agent. One has a 3D structure while the other has a 2D structure, and both show potential as effective low-dimensional magnetic materials.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Physics, Multidisciplinary
Dongxue Chen, Zhen Lian, Xiong Huang, Ying Su, Mina Rashetnia, Lei Ma, Li Yan, Mark Blei, Li Xiang, Takashi Taniguchi, Kenji Watanabe, Sefaattin Tongay, Dmitry Smirnov, Zenghui Wang, Chuanwei Zhang, Yong-Tao Cui, Su-Fei Shi
Summary: This paper reports the observation of an excitonic insulator in an angle-aligned monolayer WS2/bilayer WSe2 moire superlattice. By tuning the valence band in the second WSe2 layer to overlap with the moire miniband in the first WSe2 layer, the coexistence of electrons and holes is achieved, resulting in the formation of an excitonic insulator with a high transition temperature.
Article
Multidisciplinary Sciences
Dongxue Chen, Zhen Lian, Xiong Huang, Ying Su, Mina Rashetnia, Li Yan, Mark Blei, Takashi Taniguchi, Kenji Watanabe, Sefaattin Tongay, Zenghui Wang, Chuanwei Zhang, Yong-Tao Cui, Su-Fei Shi
Summary: In this study, the layer degree of freedom was introduced to the WSe2/WS2 moire superlattice by changing the number of layers of WSe2. Systematic changes in the optical spectra of moire excitons were observed, along with significant modifications in the energy resonances of moire excitons in multilayer WSe2/monolayer WS2 moire superlattice. The additional WSe2 layers also impacted the electronic correlation strength.
NATURE COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
Dmitry Ovchinnikov, Jiaqi Cai, Zhong Lin, Zaiyao Fei, Zhaoyu Liu, Yong-Tao Cui, David H. Cobden, Jiun-Haw Chu, Cui-Zu Chang, Di Xiao, Jiaqiang Yan, Xiaodong Xu
Summary: The authors of this study have created Chern insulator junctions between domains with different Chern numbers in MnBi2Te4, enabling the basic operation of a topological circuit. By controlling the Chern numbers of the individual domains, the chiral edge current can be split, rerouted, or switched off, offering potential applications in energy-efficient information transmission.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Yang Ge, Lingxiu Chen, Chengxin Jiang, Jianlong Ji, Qiuyun Tan, Douxing Pan, Wendong Zhang, Riguang Zhang, Eli Janzen, James H. Edgar, Shengbo Sang, Haomin Wang
Summary: In this study, triangular zigzag-edged graphene nanoflakes (GNFs) were successfully synthesized and found to exhibit high magnetization. Density functional theory calculations revealed that this magnetic property is a result of superexchange interactions among unpaired electrons at the zigzag C-BN interface. This research provides a promising platform for experimentally achieving GNFs with high electron spin states.
Article
Nanoscience & Nanotechnology
Chengxin Jiang, Lingxiu Chen, Huishan Wang, Chen Chen, Xiujun Wang, Ziqiang Kong, Yibo Wang, Haomin Wang, Xiaoming Xie
Summary: Graphene on hexagonal boron nitride (h-BN) demonstrates excellent electrical properties, which are affected by its domain size and boundaries. Chemical vapor deposition (CVD) is a hopeful method for large graphene crystal growth, but increasing the coverage of monolayer graphene on h-BN remains a challenge due to weak control of nucleation and vertical growth. In this study, an auxiliary source strategy using silicon carbide and methyl methacrylate is adopted to enhance graphene nucleation density and achieve continuous graphene films on h-BN. By optimizing the growth temperature, vertical accumulation of graphitic materials can be suppressed. This work provides an effective approach for preparing continuous graphene film on h-BN and offers insights for the growth of high-quality graphene.
Article
Nanoscience & Nanotechnology
Runhan Xiao, Shuang Wang, Yan Chen, Tianhao Tan, Yanping Sui, Ziqiang Kong, Haomin Wang, Sunwen Zhao, Zhiying Chen, Yanhui Zhang, Dong Wang, Jianlu Wang, Guanghui Yu
Summary: Compared with binary TMDCs, ternary alloys or heterojunctions have more properties. The acidity and alkalinity of precursor solutions have significant effects on the epitaxial growth of TMDCs. Acidic solutions lead to the formation of MoxW1-xS2 ternary alloys, while alkaline solutions result in MoS2/WS2 lateral heterojunctions with sharp boundaries. The controllable synthesis of different types of TMDCs can be achieved by regulating acidity and alkalinity.
ACS APPLIED NANO MATERIALS
(2023)
Review
Nanoscience & Nanotechnology
Yibo Wang, Huishan Wang, Chengxin Jiang, Xipin Chen, Chen Chen, Ziqiang Kong, Haomin Wang
Summary: Graphene has attracted significant attention in various fields, especially in microelectronic applications, due to its unique physical and electrical properties. However, the commonly used wet transfer technique for synthesizing graphene often leads to structural damage and surface contamination, limiting its use in high-performance devices. This review focuses on the advanced plasma treatment, which can play a crucial role in improving the quality of graphene throughout its growth and transfer process, and presents promising pathways for future applications.
Article
Chemistry, Multidisciplinary
Chen Chen, Yang Hang, Hui Shan Wang, Yang Wang, Xiujun Wang, Chengxin Jiang, Yu Feng, Chenxi Liu, Eli Janzen, James H. Edgar, Zhipeng Wei, Wanlin Guo, Weida Hu, Zhuhua Zhang, Haomin Wang, Xiaoming Xie
Summary: The bandgap of hBN nanoribbons (BNNRs) can be changed by spatial/electrostatic confinement. Water adsorption greatly reduces the bandgap of zigzag-oriented BNNRs (zBNNRs) and can tune their conductance and optical bandgaps.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Jiajun Chen, Xiaofei Yue, Yabing Shan, Huishan Wang, Jinkun Han, Haomin Wang, Chenxu Sheng, Laigui Hu, Ran Liu, Weihuang Yang, Zhi-Jun Qiu, Chunxiao Cong
Summary: This study reports the influence of twist angle on interlayer excitons in the WSe2/WS2 heterostructure, and confirms the existence of direct and indirect interlayer excitons through photoluminescence and density functional theory calculations. By applying an external electric field to regulate the band structure and transition path of interlayer excitons, the regulation of interlayer exciton emission was successfully achieved.
Article
Chemistry, Multidisciplinary
Xiujun Wang, Sannian Song, Haomin Wang, Tianqi Guo, Yuan Xue, Ruobing Wang, HuiShan Wang, Lingxiu Chen, Chengxin Jiang, Chen Chen, Zhiyuan Shi, Tianru Wu, Wenxiong Song, Sifan Zhang, Kenji Watanabe, Takashi Taniguchi, Zhitang Song, Xiaoming Xie
Summary: This study demonstrates that using narrow edge-contact of graphene can effectively reduce the power consumption in PCRAM, and changing the polarity of the bias pulse can extend the cycle endurance of the memory cells. Additionally, the introduction of hexagonal boron nitride multilayer can improve the programming speed and reduce resistance drift in the memory cells.