Article
Materials Science, Multidisciplinary
Pratyay Ghosh, Tobias Mueller, Ronny Thomale
Summary: The study presents the exact dimer ground state of a quantum antiferromagnet on the maple-leaf lattice, where a coupling anisotropy for one of the three inequivalent nearest-neighbor bonds is sufficient to stabilize the dimer state.
Article
Materials Science, Multidisciplinary
Masahiro Kadosawa, Masaaki Nakamura, Yukinori Ohta, Satoshi Nishimoto
Summary: We introduce spiral boundary conditions (SBCs) as a useful tool for handling the shape of finite-size periodic clusters. Using SBCs, a lattice model for more than two dimensions can be exactly projected onto a one-dimensional (1D) periodic chain with translational invariance. Hence, the existing 1D techniques such as density-matrix renormalization group (DMRG), bosonization, Jordan-Wigner transformation, etc., can be effectively applied to the projected 1D model.
Article
Materials Science, Multidisciplinary
Wen O. Wang, Jixun K. Ding, Brian Moritz, Edwin W. Huang, Thomas P. Devereaux
Summary: This study investigates the relationship between thermal conductivity and specific heat in the half-filled 2D single-band Hubbard model. The results show that thermal conductivity tends to form a peak at low temperatures, similar to the behavior of specific heat. Further temperature reduction leads to a sharp increase in thermal conductivity, which is associated with an increasing mean-free path. These findings provide insights into the anomalous thermal conductivity in insulating cuprates.
Article
Optics
Seth T. Rittenhouse, P. Giannakeas, Nirav P. Mehta
Summary: This study investigates the two-body scattering of particles in a one-dimensional periodic potential and utilizes a convenient ansatz to separate center-of-mass and relative motion, resulting in a discrete Schrodinger equation resembling a tight-binding model. By defining distinct scattering lengths and discussing collision resonances, the research reveals the interaction between different bands and collision resonances in the excited band.
Article
Materials Science, Multidisciplinary
Martin Ulaga, Jernej Mravlje, Jure Kokalj
Summary: The study reveals that spin diffusion in the Hubbard model exhibits a non-monotonic dependence on temperature, different from charge diffusion, due to the progressive liberation of charges contributing to spin transport. Moving away from half-filling and zero magnetization increases spin diffusion, but not enough to reconcile the differences between model calculations and recent measurements on cold atoms.
Article
Chemistry, Physical
Yuhui Li, Yan-Fang Zhang, Jun Deng, Wen-Han Dong, Jia-Tao Sun, Jinbo Pan, Shixuan Du
Summary: This study introduces heteroanions into 2D crystals, breaking their symmetry and achieving ternary 2D materials with emerging topological, magnetic, and dielectric properties. The rational design strategy of multiple-anion engineering shows potential for superior properties in 2D monolayers for electronic and spintronic applications.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Rajiv R. P. Singh
Summary: We discuss the thermodynamic and magnetic properties of a competing high-spin/low-spin two-orbital two-electron model on a square lattice that may be relevant to nickelates like Ba2NiO2(AgSe)2. We focus on parameter regimes where a high-spin (S = 1) and a low-spin (S = 0) state are energetically close and discuss various exchange processes in such a system. The model we study is different from the recently proposed Kondo-necklace model, although there are similarities in terms of ground-state phases and symmetries. The properties of different phases and phase transitions can be easily distinguished experimentally.
Article
Materials Science, Multidisciplinary
Martin Ulaga, Jernej Mravlje, Peter Prelovsek, Jure Kokalj
Summary: In this study, we investigate the electronic thermal conductivity and thermal diffusion constant in the square lattice Hubbard model using the finite-temperature Lanczos method. We observe that the electronic thermal conductivity is below the expected value in almost all cases, while the mean free path is typically larger or similar to the lattice spacing. The opposite effects of quasiparticle renormalization on charge and heat diffusion constants are discussed, and the Lorenz ratio is calculated and found to differ from the Sommerfeld value.
Article
Materials Science, Multidisciplinary
A. Niyazi, D. Geffroy, J. Kunes
Summary: In this study, we explored the dynamical mean-field properties of antiferromagnetic magnons in a one-, two-, and three-orbital Hubbard model under intermediate coupling strength. The effects of anisotropy introduced by external magnetic field or single-ion anisotropy were investigated, with a continuous tuning between easy-axis and easy-plane models. It was found that ordered states and magnetic excitations are sensitive to even small breaking of SU(2) symmetry of the model, in line with spin-wave theory and general symmetry considerations.
Article
Materials Science, Multidisciplinary
Josef Willsher, Hui-Ke Jin, Johannes Knolle
Summary: In this work, we study the magnetic excitations of the triangular lattice Hubbard model and find accidental zero modes related to a classical degeneracy known from the corresponding J1-J2 Heisenberg model. We extend the order-by-disorder mechanism to explain the stability of stripe order in Hubbard systems. By condensing magnon modes, we map out the entire phase diagram in remarkable agreement with recent numerical works.
Article
Chemistry, Physical
Hongyuan Li, Shaowei Li, Mit H. Naik, Jingxu Xie, Xinyu Li, Jiayin Wang, Emma Regan, Danqing Wang, Wenyu Zhao, Sihan Zhao, Salman Kahn, Kentaro Yumigeta, Mark Blei, Takashi Taniguchi, Kenji Watanabe, Sefaattin Tongay, Alex Zettl, Steven G. Louie, Feng Wang, Michael F. Crommie
Summary: Scanning tunnelling spectroscopy and ab initio simulations have revealed a strong 3D buckling reconstruction and large in-plane strain redistribution in WSe2/WS2 moire heterostructures, leading to remarkably narrow and highly localized K-point moire flat bands. These findings contradicted previous simplified theoretical models but were in quantitative agreement with ab initio simulations capturing the full 3D structural reconstruction, highlighting the dominance of strain redistribution and 3D buckling in determining the effective moire potential in TMD heterostructures.
Article
Optics
Yabo Li, Dominik Schneble, Tzu-Chieh Wei
Summary: We investigate dynamically coupled one-dimensional Bose-Hubbard models and solve for the wave functions and energies of two-particle eigenstates. Our study reveals the existence of four different continua and three doublon dispersions in the two-particle spectrum of a system with generic interactions. The presence of doublons and their energies depend on the coupling strength between two species of bosons and the interaction strengths. We provide details on the spectrum and properties of two-particle states, and analyze the difference in time evolution under different coupling strengths and the relation between the long-time behavior of the system and the doublon dispersion. These dynamics can be observed in cold atoms and potentially simulated by digital quantum computers.
Article
Physics, Multidisciplinary
Junhyun Lee, J. H. Pixley
Summary: This theoretical work explores the emulation of twisted double bilayer graphene using ultracold atoms in multiorbital optical lattices. The quadratic band touching of Bernal stacked bilayer graphene is successfully emulated using a square optical lattice, and the effects of a twist are captured through the application of an incommensurate potential. It is discovered that under specific conditions, the quadratic band touching point can become flat, accompanied by a diverging density of states and the delocalization of plane wave eigenstates.
Article
Materials Science, Multidisciplinary
Shoubhik Mandal, Debarghya Mallick, Abhishek Banerjee, R. Ganesan, P. S. Anil Kumar
Summary: We present magnetotransport measurements on Bi1Sb1Te1.5Se1.5/RuCl3 heterostructure nanodevices. The interplay between bulk and surface transport channels in Bi1Sb1Te1.5Se1.5 (BSTS) is observed through temperature-dependent resistivity measurements. The presence of topological surface states (TSS) and electrically coupled Rashba surface states (RSS) is indicated by the observed multichannel weak antilocalization effect and nonlinear Hall effect, supported by a two-band model and analysis using the Lu-Shen model.
Article
Materials Science, Multidisciplinary
X. Cao, Y. Lu, P. Hansmann, M. W. Haverkort
Summary: The study introduces a tree tensor-network impurity solver for general multiorbital systems, capturing the entanglement structure and symmetry of impurity problems efficiently. The solver operates directly on the real-time/frequency axis, producing spectral functions with high resolution independent of energy. By optimizing the impurity bath representation, the solver effectively solves self-consistent dynamical mean-field equations and calculates various dynamical correlation functions.
Article
Nanoscience & Nanotechnology
Judith Gabel, Matthias Pickem, Philipp Scheiderer, Lenart Dudy, Berengar Leikert, Marius Fuchs, Martin Stuebinger, Matthias Schmitt, Julia Kuespert, Giorgio Sangiovanni, Jan M. Tomczak, Karsten Held, Tien-Lin Lee, Ralph Claessen, Michael Sing
Summary: Thin films of transition metal oxides are affected by oxygen adatoms on the surface, leading to the formation of an electronically dead surface layer and altering the band filling and electron correlations. It is important to consider the presence of surface apical oxygen when predicting the behavior of ultrathin films of transition metal oxides.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Physics, Multidisciplinary
Christoph P. Grams, Daniel Bruening, Severin Kopatz, Thomas Lorenz, Petra Becker, Ladislav Bohaty, Joachim Hemberger
Summary: This paper presents experimental evidence for the existence of chiral solitons in the S = 1/2 spin chain compound LiCuVO4, suggesting the presence of a quantum spin liquid state.
COMMUNICATIONS PHYSICS
(2022)
Article
Chemistry, Physical
Jonas Erhardt, Maximilian Bauernfeind, Philipp Eck, Martin Kamp, Judith Gabel, Tien-Lin Lee, Giorgio Sangiovanni, Simon Moser, Ralph Claessen
Summary: Indenene, a large gap quantum spin Hall insulator, is stabilized on SiC substrates and possesses excellent structural and electronic properties. Here, we establish a simple, robust, and scalable fabrication protocol for Indenene, which involves an initial growth stage followed by a short anneal to control the coverage of indium. The specific structural and electronic properties of different coverages produce distinct experimental surface characterization, providing an efficient metric for synthesizing large scale high-quality Indenene on SiC.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Multidisciplinary Sciences
Marcin Syperek, Raul Stuhler, Armando Consiglio, Pawel Holewa, Pawel Wyborski, Lukasz Dusanowski, Felix Reis, Sven Hofling, Ronny Thomale, Werner Hanke, Ralph Claessen, Domenico Di Sante, Christian Schneider
Summary: The optical spectroscopy of ultimately thin materials has greatly benefited our understanding of collective excitations in low-dimensional semiconductors. The authors of this study report the observation of room temperature excitons in a single layer of bismuth atoms epitaxially grown on a SiC substrate, a material with non-trivial global topology. These excitonic and topological physics arise from the same electronic structure.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Yan Tan, Yijie Wang, Aoshuang Li, Yongqi Zhang, Yuzhong Zhang, Chuanwei Cheng
Summary: In this study, a highly efficient bifunctional electrocatalyst consisting of biphasic FeCo nanoparticles and Fe, Co single atoms embedded in N-doped carbon nanotube arrays was designed and fabricated. The as-prepared electrocatalyst exhibited excellent bifunctional oxygen activity and was used as binder-free air cathodes for aqueous zinc-air batteries and flexible quasi-solid-state zinc-air batteries, demonstrating high specific capacity and stability.
MATERIALS TODAY ENERGY
(2022)
Article
Chemistry, Multidisciplinary
Xiao-Fang Ouyang, Yu-Zhong Zhang, Lu Wang, De-Sheng Liu
Summary: Using density functional theory calculations, we predict that bilayer silicene can exhibit an interlayer antiferromagnetic ground state, resulting in half-metallicity by adsorbing non-magnetic atoms. We explain that this half-metallicity is induced by the charge transfer from the adatom to silicene, causing the split of antiferromagnetic degeneracy. Our findings present a new avenue for the development of silicene-based electronic and spintronic devices.
Article
Physics, Condensed Matter
Miao Meng, Siqian Liu, Dongsheng Song, Xi Zhang, Haifeng Du, Haoliang Huang, Huaying Liu, Zhangao Sun, Chenguang Mei, Huaixin Yang, Huanfang Tian, Yalin Lu, Yuzhong Zhang, Jianqi Li, Yonggang Zhao
Summary: This study investigates the temperature dependences of resistivity, Hall effect and magnetoresistance of FeTe thin films with different amounts of excess Fe and oxygen. The results show that the oxygen-annealed samples exhibit positive Hall coefficients, while the vacuum-annealed samples transition from positive to negative below 50 K. Both the resistivity and Hall coefficient of all samples display a significant drop at around 50 K-75 K, indicating the coexistence of superconductivity and antiferromagnetic order in the oxygen-annealed samples. Additionally, the oxygen-annealed samples show dominant negative magnetoresistance, while the vacuum-annealed samples exhibit both positive and negative values. Oxygen annealing is found to reduce the excess Fe in FeTe, which has been previously overlooked. The findings are discussed in relation to the understanding of oxygen-annealed FeTe thin films in comparison with FeSe1-x Te (x).
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Chemistry, Multidisciplinary
Bing Liu, Tim Wagner, Stefan Enzner, Philipp Eck, Martin Kamp, Giorgio Sangiovanni, Ralph Claessen
Summary: By synthesizing ultrathin Sb films on semi-insulating InSb(111)A substrate, researchers observe a pronounced moire pattern on the Sb films and confirm experimentally that the topological surface state persists and shifts toward lower binding energies with a decrease in Sb thickness, in agreement with theoretical predictions.
Article
Materials Science, Multidisciplinary
Ming-Cui Ding, Bing-Ying Pan, Gang Zhao, Yu-Zhong Zhang
Summary: The electronic structures of LaFe2As2 and CaFe2As2 in the UT and CT phases were studied using density functional theory and tight-binding models. It was found that the 4p states of As contribute significantly to the relative instability between (pi, pi, pi) and (0, 0, pi) of Pauli susceptibility x0, which may facilitate electron pairing. This suggests that the 3d states of Fe alone are insufficient to capture the superconducting properties of iron-based superconductors. These results provide qualitative criteria for understanding the superconducting properties of LaFe2As2 and CaFe2As2, emphasizing the importance of considering the 4p states of As and interlayer cation states in further studies on iron-based superconductors.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Chemistry, Physical
Lenart Dudy, Piotr Chudzinski, Julian Aulbach, Victor Rogalev, Joerg Schaefer, Ralph Claessen
Summary: In this study, we investigated the temperature dependence of the metallic-like bands of Si(553)-Au using angular-resolved photoemission spectroscopy. By overcoming the challenges posed by surface stability and photo-voltage effects, we were able to extract changes in band-filling and Fermi-velocity. Our findings shed light on the nature of the low-temperature phase of the step edge in Si(553)-Au and rule out a structural-related phase transition.
Article
Physics, Multidisciplinary
P. Kagerer, C. I. Fornari, S. Buchberger, T. Tschirner, L. Veyrat, M. Kamp, A. V. Tcakaev, V. Zabolotnyy, S. L. Morelhao, B. Geldiyev, S. Mueller, A. Fedorov, E. Rienks, P. Gargiani, M. Valvidares, L. C. Folkers, A. Isaeva, B. Buechner, V. Hinkov, R. Claessen, H. Bentmann, F. Reinert
Summary: Inducing a magnetically-induced gap in the Dirac point of a three-dimensional topological insulator can result in dissipationless charge and spin currents. In this study, the authors use a ferromagnetic extension technique to create a robust 2D ferromagnetic material on the surface of a 3D topological insulator. The results demonstrate the opening of a sizable magnetic gap in the 2D ferromagnetic phase, while the surface remains gapless in the paramagnetic phase.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Philipp Eck, Carmine Ortix, Armando Consiglio, Jonas Erhardt, Maximilian Bauernfeind, Simon Moser, Ralph Claessen, Domenico Di Sante, Giorgio Sangiovanni
Summary: The recently introduced classification of two-dimensional insulators in terms of topological crystalline in-variants has been extended to quantum spin Hall insulators, and an experimental fingerprint of the obstruction has been measured.
Article
Materials Science, Multidisciplinary
Suhua Jin, Yunyouyou Xia, Wujun Shi, Jiayu Hu, Ralph Claessen, Werner Hanke, Ronny Thomale, Gang Li
Summary: The chiral edge modes in the topological quantum anomalous Hall effect are crucial for future quantum technology and spintronics applications. This study proposes Al2O3 as an ideal substrate for atomic monolayers of Bi and group-III elements, where a large-gap quantum spin Hall effect can be realized. Additional half-passivation with nitrogen suggests a topological phase transition to a large-gap QAH insulator. Effective tight-binding modeling shows that the system is dominated by px, py orbitals with a subdominant pz orbital contribution. The topological phase transition is induced by Zeeman splitting, with no significant role played by off-diagonal spin exchange.
Article
Materials Science, Multidisciplinary
Yunyouyou Xia, Suhua Jin, Jiayu Hu, Ralph Claessen, Werner Hanke, Ronny Thomale, Gang Li
Summary: We extend the px-py large-gap scenario to the band inversion systems and exemplify the mechanism with a family of III-Bi honeycomb monolayers on SiO2. This work enriches the research field of large-gap quantum spin Hall systems.
Article
Materials Science, Multidisciplinary
Xiu-Cai Jiang, Yi-Yuan Zhao, Yu-Zhong Zhang
Summary: The article presents a way to tune the tiny gap in twisted bilayer graphene into a large gap. Through comprehensive understanding of the physical origin of gap opening, the study reveals that effective interlayer hopping and charge imbalance are key factors in creating a gap. Based on tight-binding calculations, the researchers suggest using periodic transverse inhomogeneous pressure to tune the interlayer hoppings and create a gap of over 100 meV. First-principles calculations further confirm the feasibility of this approach.