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
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
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
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
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
Chemistry, Multidisciplinary
Qiangsheng Lu, Congcong Le, Xiaoqian Zhang, Jacob Cook, Xiaoqing He, Mohammad Zarenia, Mitchel Vaninger, Paul F. Miceli, David J. Singh, Chang Liu, Hailang Qin, Tai-Chang Chiang, Ching-Kai Chiu, Giovanni Vignale, Guang Bian
Summary: This study proposes a new method to achieve flat band physics in monolayer graphene by substrate modulation. Experimental results on the graphene/SiC heterostructure demonstrate that substrate modulation leads to Dirac fermion cloning and the proximity of the two Dirac cones in monolayer graphene. Theoretical modeling confirms the cloning mechanism and predicts the emergence of moire flat bands at certain magic lattice constants of the substrate. This study suggests that epitaxial single monolayer graphene on suitable substrates is a promising platform for exploring exotic many-body quantum phases arising from interactions between Dirac electrons.
ADVANCED MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Seth M. Davis, Fengcheng Wu, Sankar Das Sarma
Summary: In this study, we calculated the contribution of acoustic phonon scattering to the doping and temperature dependence of the electrical resistivity of twisted bilayer graphene (TBLG). We found that the band geometry plays a crucial role in determining the resistivity, and were able to explain the existence of resistance peaks observed in experiments.
Article
Materials Science, Multidisciplinary
Jiseon Shin, Bheema Lingam Chittari, Jeil Jung
Summary: Tri-layer graphene with twisted middle layer has recently shown correlated phases and superconductivity near its magic angle, with distinct electronic structure influenced by twist angle, interlayer potential difference, and top-bottom layer stacking.
Article
Materials Science, Multidisciplinary
Jonah Herzog-Arbeitman, Aaron Chew, B. Andrei Bernevig
Summary: Bloch's theorem is crucial in topological band theory, but is broken by a perpendicular magnetic field, posing challenges in studying topological systems in strong flux. Moire materials have made this problem relevant in experiments, and this paper focuses on finding a solution. The authors construct a mathematical framework and analyze the behaviors of systems under 2n flux using a simple square lattice model and the Bistritzer-MacDonald Hamiltonian.
Article
Multidisciplinary Sciences
Zhen Ma, Shuai Li, Ya-Wen Zheng, Meng-Meng Xiao, Hua Jiang, Jin-Hua Gao, X. C. Xie
Summary: Twisted trilayer graphene is a simple realistic system with flat bands and nontrivial topology, making it an ideal platform for studying strongly correlated physics. The band structures of twisted TLG are influenced by the twist angle and perpendicular electric field, resulting in unique correlated states compared to other graphene structures.
Article
Chemistry, Multidisciplinary
Yiwei Li, Shihao Zhang, Fanqiang Chen, Liyang Wei, Zonglin Zhang, Hanbo Xiao, Han Gao, Moyu Chen, Shijun Liang, Ding Pei, Lixuan Xu, Kenji Watanabe, Takashi Taniguchi, Lexian Yang, Feng Miao, Jianpeng Liu, Bin Cheng, Meixiao Wang, Yulin Chen, Zhongkai Liu
Summary: Magic-angle twisted trilayer graphene (MATTG) has shown rich and unique properties, including superconductivity and distinct band structure. Experimental measurements reveal the coexistence of different bands in MATTG, which is crucial for further understanding its unconventional superconductivity.
ADVANCED MATERIALS
(2022)
Article
Multidisciplinary Sciences
Bhaskar Ghawri, Phanibhusan S. Mahapatra, Manjari Garg, Shinjan Mandal, Saisab Bhowmik, Aditya Jayaraman, Radhika Soni, Kenji Watanabe, Takashi Taniguchi, H. R. Krishnamurthy, Manish Jain, Sumilan Banerjee, U. Chandni, Arindam Ghosh
Summary: When the relative rotation of twisted bilayer graphene is close to the magic angle, it exhibits interaction-driven phases with correlation-induced ground states and a possibility of non-Fermi liquid excitations. However, the manifestation of non-Fermi liquid effects in the transport properties of twisted bilayer graphene remains ambiguous.
NATURE COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Zhen-Bing Dai, Zhiqiang Li, Yan He
Summary: The study investigates the optical response of bilayer graphene with a kink potential and finds that the one-dimensional chiral states localized at the domain wall significantly contribute to the local optical conductivity. The effects of domain wall states on optical conductivity can be detected through spatially and frequency-resolved spectroscopic features. The spatial distribution of local optical conductivity can provide important information on bound states and topological domain wall states when the domain wall region is broad.
Article
Chemistry, Physical
M. Alihosseini, S. Ghasemi, S. Ahmadkhani, M. Alidoosti, D. Nasr Esfahani, F. M. Peeters, M. Neek-Amal
Summary: The paper uses a multiscale modeling approach to investigate the band flattening of oxidized monolayer graphene, finding that the width of the flat bands can be tuned by various factors including strain, electric field, and functional group density. Conducting state transitions and impurity-induced flat bands were observed, providing new insights into research on band flattening in monolayer graphene.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Adam Eaton, Yantao Li, H. A. Fertig, Babak Seradjeh
Summary: This study investigates the presence of flat bands in stacked graphene multilayers with small relative twist angles. The effect of Dirac point asymmetry and Fermi velocity differences between layers is considered. The results show that despite this asymmetry, the flat band phenomenon persists. The magic angles can be tuned by controlling the screening in the bilayer system or the twist angles of the outer layers in the tetralayer system. Notably, the quantitative values of the magic angles are increased in the models.
Article
Materials Science, Multidisciplinary
Young Woo Choi, Hyoung Joon Choi
Summary: The study reveals that the interband tunneling properties in lateral black phosphorus junctions are significantly influenced by the anisotropic pseudospin structure, with different tunneling behaviors observed for different junction directions. Junctions of band-gap inverted BP exhibit variations in tunneling effects based on junction direction, suggesting potential in developing high-performance devices.
Article
Physics, Multidisciplinary
Young Woo Choi, Marvin L. Cohen
Summary: We investigated the electromigration forces for weakly bonded adsorbates on graphene using density-functional based calculations. The results showed that the nature of electromigration forces depends critically on the energy level alignment between the adsorbate state and the Fermi level of the graphene. For resonant adsorbates, the electromigration force is dominated by the electron wind force, while for nonresonant adsorbates, it is essentially the direct force dependent on the adsorbate charge. Moreover, we demonstrated that the magnitude of electromigration forces can be continuously adjusted through electrostatic gating for resonant adsorbates.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Yangjin Lee, Young Woo Choi, Kihyun Lee, Chengyu Song, Peter Ercius, Marvin L. Cohen, Kwanpyo Kim, Alex Zettl
Summary: In this study, one-dimensional (1D) chains of GeX2 (X = S or Se) were reported, and the tetrahedral connectivity was modified at the single-chain limit by precise tuning of the edge-and corner-sharing modes between GeX2 blocks, achieved through diameter-dependent 1D confinement inside a carbon nanotube. Atomic-resolution scanning transmission electron microscopy directly confirmed the existence of two distinct types of GeX2 chains. Density functional theory calculations corroborated the diameter-dependent stability of the system and revealed an intriguing electronic structure that sensitively depended on tetrahedral connectivity and composition.
Article
Chemistry, Multidisciplinary
Jangwon Kim, Youjin Lee, Young Woo Choi, Taek Sun Jung, Suhan Son, Jonghyeon Kim, Hyoung Joon Choi, Je-Geun Park, Jae Hoon Kim
Summary: We conducted a terahertz spectroscopic study and density functional theory analysis on Nb3Cl8 and Nb3I8, two van der Waals semiconductors. The observed infrared-active phonon modes in the terahertz region matched well with our calculations. We found that the phonon spectra of Nb3Cl8 were consistent with a structural transition at 90 K, while Nb3I8 showed no significant temperature or magnetic field dependence in the phonon spectra. Our study establishes a connection between structural properties and paramagnetic-nonmagnetic transitions in these compounds.
Article
Chemistry, Multidisciplinary
Soo Yeon Lim, Han-gyu Kim, Young Woo Choi, Takashi Taniguchi, Kenji Watanabe, Hyoung Joon Choi, Hyeonsik Cheong
Summary: We present a detailed analysis of the interlayer interaction dependent on the twist angle in WSe2/MoSe2 hetero-twisted bilayer (TBL) through Raman and photoluminescence studies combined with first-principles calculation. Different interlayer vibrational modes, moiré phonons, and interlayer excitonic states with distinct characteristics are observed and identified as the twist angle evolves. Moreover, the interlayer excitons in hetero-TBLs with twist angles near 0 degrees or 60 degrees exhibit different energies and photoluminescence excitation spectra due to variations in electronic structures and carrier relaxation dynamics. These findings contribute to a better understanding of the interlayer interaction in hetero-TBLs.
Article
Chemistry, Multidisciplinary
Yangjin Lee, Young Woo Choi, Kihyun Lee, Chengyu Song, Peter Ercius, Marvin L. Cohen, Kwanpyo Kim, Alex Zettl
Summary: This paper reports on a family of 1D magnetic van der Waals materials with composition MX3, prepared in fully-isolated fashion within the protective cores of carbon nanotubes. Unique structures different from the well-known 2D honeycomb lattice MX3 structure are identified through atomic-resolution scanning transmission electron microscopy. Density functional theory calculations reveal charge-driven reversible magnetic phase transitions.
ADVANCED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Mancheon Han, Hyoung Joon Choi
Summary: We have developed a reliable parameter-free analytic continuation method for quantum many-body calculations. The method utilizes a kernel grid, a causal spline, a regularization approach, and the L-curve criterion. Additionally, we have introduced the L-curve averaged deviation to estimate the precision of our analytic continuation. To handle statistically obtained data more efficiently, we have also developed a bootstrap-averaged analytic continuation method. The results demonstrate the effectiveness of our method in converging to the exact spectral function when applied to imaginary-frequency Green's function with added statistical error. Furthermore, we have successfully identified a non-Fermi-liquid behavior in the two-orbital Hubbard model using our analytic continuation method. This research significantly contributes to improving the accuracy and clarity of conclusions drawn from imaginary-time quantum many-body calculations.
Article
Materials Science, Multidisciplinary
Mancheon Han, Hyoung Joon Choi
Summary: Researchers develop a causal optimization method to ensure causality in numerical calculations of Green's functions in interacting electron systems. They find that intermediate-frequency behaviors of Green's functions are determined solely by causality, and their method provides a basis for improving stability and efficiency of numerical simulations of quantum many-body systems.
Article
Materials Science, Multidisciplinary
Han-gyu Kim, Hyoung Joon Choi
Summary: We studied the quasiparticle band structures, spontaneous polarization, and spin-splitting in noncentrosymmetric gamma-GeSe, finding it to possess semiconductor properties with spontaneous polarization resulting from small charge transfer between layers, and more significant spin-splitting in the valence band.
JOURNAL OF MATERIALS CHEMISTRY C
(2021)
Article
Materials Science, Multidisciplinary
Han-gyu Kim, Hyoung Joon Choi
Summary: First-principles density functional theory (DFT) and GW calculations were used to investigate the electronic structures of bulk and few-layer PdSe2. The obtained quasiparticle band structures and electronic structure parameters provide a foundation for both basic research and device applications.
Article
Materials Science, Multidisciplinary
Han-gyu Kim, Hyoung Joon Choi
Summary: This study accurately determines the work function, ionization energy, and electron affinity of few-layer and bulk MX2 through density functional theory and GW calculations, analyzing the impact of thickness on these properties and discussing the band alignment types of these compounds.
