Article
Chemistry, Multidisciplinary
Felix Winterer, Anna M. Seiler, Areg Ghazaryan, Fabian R. Geisenhof, Kenji Watanabe, Takashi Taniguchi, Maksym Serbyn, R. Thomas Weitz
Summary: In this study, the formation of Dirac gullies and the interaction-induced breakdown of gully coherence were explored through magnetotransport measurements in high-quality Bernal-stacked trilayer graphene. The emergence of Dirac gullies in the quantum Hall regime and the control of electron-electron interactions through electric and magnetic fields were observed, leading to the lifting of gully degeneracy and the formation of a correlated ground state.
Article
Astronomy & Astrophysics
Kazuki Hasebe
Summary: This study investigates the SO(5) Landau problem in the background of the SO(4) monopole gauge field using techniques of non-linear realization of quantum field theory. It analyzes the energy levels distribution, wave function form, and constructs Laughlin-like wavefunctions.
Article
Chemistry, Multidisciplinary
Alexander Popert, Yuya Shimazaki, Martin Kroner, Kenji Watanabe, Takashi Taniguchi, Atac Imamoglu, Tomasz Smolenski
Summary: Graphene and its heterostructures have unique properties for studying strongly correlated electronic phases. However, the lack of a robust energy bandgap has limited optical access to these phases. This study demonstrates an all-optical spectroscopic tool using excited Rydberg excitons in an adjacent transition metal dichalcogenide monolayer to probe electronic correlations in graphene. The technique has submicron spatial resolution, circumventing spatial inhomogeneities and enabling optical studies of correlated states in optically inactive atomically thin materials.
Article
Chemistry, Multidisciplinary
Priya Tiwari, Divya Sahani, Atasi Chakraborty, Kamal Das, Kenji Watanabe, Takashi Taniguchi, Amit Agarwal, Aveek Bid
Summary: In this study, the experimental evidence of the time-reversal symmetric Hall effect in high-mobility graphene-WSe2 heterostructures is provided. This dissipative Hall effect is linear and its sign depends on the charge carriers. It persists up to room temperature and can be tuned using an external electric field. The strain induced by lattice mismatch or alignment angle inhomogeneity breaks the inversion symmetry and produces anisotropic bands in graphene, leading to the appearance of a time-reversal symmetric Hall effect.
Article
Chemistry, Physical
Tuan Khanh Chau, Dongseok Suh, Haeyong Kang
Summary: This study investigates the influence of individual grain boundaries (GBs) on the quantum Hall effect (QHE) in monolayer chemical vapor deposition (CVD) graphene. It finds that the scattering of GBs only affects the longitudinal resistance (R-xx) in the low carrier concentration region, while the standard QHE of monolayer graphene can be observed regardless of the stitching angle of the GB. Additionally, a controlled device with an added metal bar is introduced, showing that only R-xx is affected by nonzero resistance, while the Hall resistance (R-xy) exhibits well-quantized plateaus in the QH state.
Article
Materials Science, Multidisciplinary
Udit Khanna, Ke Huang, Ganpathy Murthy, H. A. Fertig, Kenji Watanabe, Takashi Taniguchi, Jun Zhu, Efrat Shimshoni
Summary: Bilayer graphene exhibits a rich phase diagram in the quantum Hall regime, and the presence of various fractional quantum Hall states suggests the occurrence of a quantum phase transition and Kekule bond ordering.
Article
Materials Science, Multidisciplinary
Edward Schwartz, Hamed Vakili, Moaz Ali, Alexey A. Kovalev
Summary: This study investigates the interplay between vorticity and spin currents in an easy-plane magnet, showing the generation of transverse spin currents accompanying the flow of vorticity, known as the spin Hall effect of vorticity. The research also examines the effect across the BKT transition and highlights the role of dissipation and spin nonconservation in the transition from spin superfluidity to diffusive spin transport. The results of this study pave the way for low power computing devices based on vorticity and spin flows that can propagate over long distances.
Article
Multidisciplinary Sciences
Alexis Coissard, Adolfo G. Grushin, Cecile Repellin, Louis Veyrat, Kenji Watanabe, Takashi Taniguchi, Frederic Gay, Herve Courtois, Hermann Sellier, Benjamin Sacepe
Summary: By performing scanning tunneling spectroscopy on hexagonal boron nitride, this study shows that quantum Hall edge channels in graphene are confined to the crystal edges and do not undergo reconstruction with additional non-topological upstream modes. This has significant implications for electron and heat transport experiments in graphene-based systems and other 2D crystalline materials.
Article
Chemistry, Physical
Yang Zhang, Qiunan Xu, Klaus Koepernik, Roman Rezaev, Oleg Janson, Jakub Zelezny, Tomas Jungwirth, Claudia Felser, Jeroen van den Brink, Yan Sun
Summary: The study found a strong relationship between spin Hall conductivity (SHC) and crystalline symmetry, with large SHC typically associated with mirror symmetry-protected nodal line band structures. They also identified 11 materials with substantial SHC, comparable to or larger than that of Pt. Different types of spin currents were found, and it was discovered that they can be obtained by rotating applied electrical fields.
NPJ COMPUTATIONAL MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Zhenjiu Wang, David J. Luitz, Inti Sodemann Villadiego
Summary: This study investigates the continuum model of the interface between charge neutral graphene and vacuum in the quantum Hall regime. A quantum Monte Carlo method is used to explore the interplay of topology and strong interactions in graphene quantum Hall edges. The researchers focus on the topological phase transition and find peculiar behaviors in the edge dispersion and bulk charge susceptibility.
Article
Physics, Multidisciplinary
D. Jahani, O. Akhavan, Alidoust Ghatar
Summary: A strong Goos-Hanchen (GH) effect at a prism-graphene interface in the quantum Hall effect (QHE) condition is reported. By fully quantum describing the temperature-dependent surface conductivity of graphene in the unconventional quantum Hall regime, magnetically strong tunable QHE GH shifts are observed. The study derives generalized Fresnel coefficients with antisymmetric conductivity tensor for the Kerr phase of linearly polarized incident light. Furthermore, it is demonstrated that at low temperatures, GH shifts exhibit plateaus as the magnetic field intensity increases. This quantum modulation of the GH effect in graphene by applied magnetostatic bias may provide new opportunities for optical devices and QHE sensing applications in 2D materials.
Article
Chemistry, Multidisciplinary
Lingfei Zhao, Ethan G. Arnault, Trevyn F. Q. . Larson, Zubair Iftikhar, Andrew Seredinski, Tate Fleming, Kenji Watanabe, Takashi Taniguchi, Francois Amet, Gleb Finkelstein
Summary: The vanishing band gap of graphene has posed challenges for creating high-quality quantum point contacts. However, recent advances have allowed split-gate QPCs to operate using the highly resistive v = 0 state. Researchers have developed a simple method of fabricating QPCs by etching a narrow trench in the graphene sheet, separating the conducting channel from self-aligned graphene side gates. This technique has enabled the creation and study of a quantum Hall interferometer.
Article
Physics, Applied
K. Funayama, J. Hirotani, A. Miura, H. Tanaka
Summary: This article investigates the robustness of topological edge modes inspired by the quantum spin Hall effect in a honeycomb-shaped thermal diffusion system. It is found that the robustness of the edge modes deteriorates due to the contributions of C-6 symmetry breaking and interactions between multiple boundaries. However, strong C-6 symmetry breaking can improve the robustness degraded by such boundary interactions.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Multidisciplinary
Yawar Mohammadi, Samira Bahrami
Summary: This paper investigates the effects of Y-shaped Kekule bond texture on the transport coefficients of Kekule-patterned graphene. It is found that this texture lifts the valley degeneracy of all levels except the zero mode, resulting in additional plateaus in the Hall conductivity and a split of the peaks in the longitudinal conductivity. The results also indicate that DC Hall conductivity measurements can determine the amplitude of the Kekule bond texture.
Article
Materials Science, Multidisciplinary
M. Tanaka, K. Watanabe, T. Taniguchi, K. Nomura, S. Tarucha, M. Yamamoto
Summary: Research on temperature-induced phase transitions of the quantum Hall system has been limited. In this study, we measured the pure bulk conductivity of a quantum Hall antiferromagnetic state in bilayer graphene and revealed a two-step phase transition associated with the breaking of long-range order. This finding is fundamental for understanding electron correlation in quantum Hall systems.
Article
Engineering, Environmental
Fan Zhang, Yi Liu, Kai-Qiang Ma, Heng Yan, Yue Luo, Feng-Cheng Wu, Chu-Ting Yang, Sheng Hu, Shu-Ming Peng
Summary: This study successfully prepared mesoporous silica materials with high selectivity, which can effectively reduce wastewater contaminated with uranium. The experimental results showed that the material had a strong affinity for uranium under low acidic conditions and exhibited good reusability.
JOURNAL OF HAZARDOUS MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Yuhao Li, Minmin Xue, Hua Fan, Cun-Fa Gao, Yan Shi, Yang Liu, Kenji Watanabe, Takashi Tanguchi, Yue Zhao, Fengcheng Wu, Xinran Wang, Yi Shi, Wanlin Guo, Zhuhua Zhang, Zaiyao Fei, Jiangyu Li
Summary: In this study, a twisted trilayer graphene double-moire superlattice was investigated using conductive atomic force microscopy. Two sets of moire superlattices were observed, and different rotational symmetries of current as well as anomalous current at the A-A stacking site were discovered. These behaviors can be understood through atomic reconstruction.
Article
Physics, Multidisciplinary
Haining Pan, Ming Xie, Fengcheng Wu, Sankar Das Sarma
Summary: This article presents a theoretical study on the quantum phase diagram of MoTe2/WSe2, using a self-consistent calculation method to obtain various results related to filling factors and interactions, including stable topological insulators, competing states, and topological charge density waves.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Hao Wang, Yao Wen, Xiaoxu Zhao, Ruiqing Cheng, Lei Yin, Baoxing Zhai, Jian Jiang, Zhongwei Li, Chuansheng Liu, Fengcheng Wu, Jun He
Summary: The heteroepitaxial growth of ferromagnetic CuCr2Te4 nanosheets on Cr2Te3 and mica by chemical vapor deposition is reported. The CuCr2Te4 nanosheets on mica exhibit thickness-dependent ferromagnetism with a decrease in Curie temperature (T-C) and an enhancement of perpendicular magnetic anisotropy. Moreover, the lattice-matched heteroepitaxial ultrathin CuCr2Te4 on Cr2Te3 shows an enhanced robust ferromagnetism with an increased T-C due to interfacial charge transfer. This work provides a method to construct robust room-temperature 2D magnetic heterostructures for functional spintronic devices.
ADVANCED MATERIALS
(2023)
Article
Engineering, Environmental
Qiyuan Liu, Huading Shi, Yanfei An, Jin Ma, Wenhao Zhao, Yajing Qu, Haiyan Chen, Lingling Liu, Fengcheng Wu
Summary: Rare earth elements (REEs), considered as emerging pollutants, have been increasingly released into the environment due to their extensive use in industries, agriculture, and high-tech devices. However, limited research has been conducted on REEs in urban soils. The objective of this study was to investigate the potential sources and risks of REEs in the urban environment. The study analyzed the concentration and distribution of REEs in urban park soils and used microgeochemical and random forest methods to determine the pollution sources of REEs. The results showed that the high concentrations of REEs were mainly found in the western part of Beijing near an industrial area, confirming the anthropogenic pollution sources from industry and traffic. Risk assessment indicated that the daily intake of REEs for both children and adults was below the reference threshold, suggesting negligible health risks.
JOURNAL OF HAZARDOUS MATERIALS
(2023)
Article
Physics, Multidisciplinary
Ming Xie, Haining Pan, Fengcheng Wu, Sankar Das Sarma
Summary: The effect of interelectron Coulomb interactions on the displacement field induced topological phase transition in transition metal dichalcogenide heterobilayers is studied. It is found that a nematic excitonic insulator phase can exist when the interlayer tunneling is weak or when the Coulomb interaction is not strongly screened. The nematicity arises from the frustration between the nontrivial spatial structure of the interlayer tunneling and the interlayer coherence induced by the Coulomb interaction.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Qianying Hu, Zhen Zhan, Huiying Cui, Yalei Zhang, Feng Jin, Xuan Zhao, Mingjie Zhang, Zhichuan Wang, Qingming Zhang, Kenji Watanabe, Takashi Taniguchi, Xuewei Cao, Wu-Ming Liu, Fengcheng Wu, Shengjun Yuan, Yang Xu
Summary: Researchers demonstrate the spatial confinement and manipulation of Rydberg moire excitons through two-dimensional moire superlattices, indicating their potential for quantum technologies.
Article
Materials Science, Multidisciplinary
Tsung-Sheng Huang, Yang-Zhi Chou, Christopher L. Baldwin, Fengcheng Wu, Mohammad Hafezi
Summary: We develop a systematic theory for excitons subject to Fermi-Hubbard physics in moire twisted transition metal dichalcogenides (TMDs). We find significantly narrower exciton bandwidths in the presence of Hubbard physics, serving as a potential experimental signature of strong correlations. Our work provides guidelines for future exploration of strongly correlated excitons in triangular Hubbard systems such as twisted TMD heterobilayers.
Article
Materials Science, Multidisciplinary
Jiabin Yu, Ming Xie, Fengcheng Wu, Sankar Das Sarma
Summary: Signatures of nematic nodal superconductivity have been observed in magic angle twisted bilayer graphene. Researchers propose a general topological mechanism explaining how nematic pairing leads to nodal superconductivity in this material.
Article
Materials Science, Multidisciplinary
Seth M. Davis, Yang-Zhi Chou, Fengcheng Wu, Sankar Das Sarma
Summary: We calculate the theoretical contribution of scattering by acoustic phonons to the doping and temperature dependence of electrical resistivity in Bernal bilayer graphene (BBG) and rhombohedral trilayer graphene (RTG). The nontrivial geometric features of the band structures of these systems strongly influence the resistivity's temperature and doping dependencies. Our focus on BBG and RTG is motivated by recent experiments in these systems that have discovered exotic low-temperature superconductivity. The understanding of the influence of band geometry on transport is crucial in these systems.
Article
Materials Science, Multidisciplinary
Zhengzhi Wu, Yi-Ming Wu, Fengcheng Wu
Summary: We show that the pair density wave (PDW) susceptibility can be enhanced to the same level as the BCS susceptibility through a valley-contrasting flux in moire systems. The PDW order becomes the leading instability under certain conditions, while a topological loop current order emerges if the Fermi surface with conventional Van Hove singularities is perfectly nested. The flux can be controlled experimentally in moire systems based on graphene and transition metal dichalcogenides.
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
Xun-Jiang Luo, Fengcheng Wu
Summary: This paper generalizes the Benalcazar-Bernevig-Hughes (BBH) model to arbitrary dimensions and proposes a general boundary projection method for extracting the boundary Hamiltonians. By analyzing the analytical solution and chiral symmetry, the dimensional hierarchy of BBH models is revealed.
Article
Materials Science, Multidisciplinary
Yongxin Zeng, Allan H. MacDonald
Summary: This paper examines the influence of moiré patterns in semiconductor heterobilayers on exciton and trion states, comparing the differences to the case of excitons and trions in semiconductor quantum dots in the limit of strong moiré modulation potentials. The strategies for using optical properties as quantitative probes of moiré materials and the prospects of utilizing moiré materials to design unique light emitters are discussed.
Article
Materials Science, Multidisciplinary
B. Flebus, A. H. MacDonald
Summary: It has been found in recent experiments that phonons can be deflected by a magnetic field when flowing in response to a thermal gradient, leading to a thermal Hall effect. The ratio of phonon Hall conductivity ??H to the phonon longitudinal conductivity ??L in oxide dielectrics can exceed 10^-3 when phonon mean-free paths are longer than phonon wavelengths. Additionally, the ??H/??L ratio does not strongly depend on temperature. These observations suggest a mechanism related to phonon scattering from defects that break time-reversal symmetry, where Lorentz forces acting on charged defects result in significant skew-scattering amplitudes and related thermal Hall effects.
