Article
Materials Science, Multidisciplinary
S. Molatta, D. Opherden, J. Wosnitza, L. Opherden, Z. T. Zhang, T. Wolf, H. Loehneysen, R. Sarkar, P. K. Biswas, H-J Grafe, H. Kuehne
Summary: Recent experiments show that FeSe provides the possibility to study bulk superconductivity in the crossover regime between BCS and BEC. The research found a distinct state with large spin polarization in FeSe under strong magnetic fields along the c axis, indicating a high spatial homogeneity of the bulk superconducting state. Despite pronounced spin fluctuations, FeSe exhibits an unusual field-induced superconducting state in the BCS-BEC crossover regime.
Article
Chemistry, Physical
Benjamin Cohen-Stead, Kipton Barros, Richard Scalettar, Steven Johnston
Summary: This study investigates the relationship between electron-phonon interactions and charge-density-wave order in the bismuthate family of high-temperature superconductors. The results demonstrate that coupling to the bond-stretching modes is sufficient to reproduce the CDW transition in this system, despite a relatively small coupling. Additionally, the transition deviates from the weak-coupling Peierls' picture. This work highlights the importance of off-diagonal e-ph interactions in establishing the bismuthate phase diagram.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Die Hu, Qisi Wang, Hongliang Wo, Astrid Schneidewind, Jun Zhao
Summary: We report inelastic neutron scattering measurements of low-energy spin fluctuations in FeSe0.95S0.05 (Tc = 10 K). Our experiments revealed a resonance mode at 3.5 meV, accompanied by a spin gap below 3 meV at the stripe wave vector in the superconducting state. An abrupt enhancement of stripe spin fluctuations is found below a nematic ordering temperature of Ts = 80 K.
Article
Materials Science, Multidisciplinary
Maksymilian Sroda, Elbio Dagotto, Jacek Herbrych
Summary: Motivated by experimental evidence of exotic magnetism in low-dimensional iron-based materials, the study presents a comprehensive theoretical analysis of magnetic states in the multiorbital Hubbard ladder in the orbital-selective Mott phase. The main result is the doping vs interaction magnetic phase diagram, reproducing experimental findings on AFe(2)X(3) materials and predicting new phases.
Article
Multidisciplinary Sciences
Ilya Shipulin, Nadia Stegani, Ilaria Maccari, Kunihiro Kihou, Chul-Ho Lee, Quanxin Hu, Yu Zheng, Fazhi Yang, Yongwei Li, Chi-Ming Yim, Ruben Huehne, Hans-Henning Klauss, Marina Putti, Federico Caglieris, Egor Babaev, Vadim Grinenko
Summary: The study discovered a new fermionic quadrupling condensate that breaks the Z(2) time-reversal symmetry. By detecting the specific heat, researchers found specific anomalies above the superconducting critical temperature, which are associated with the broken time-reversal symmetry.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
O. A. Moreno Segura, K. Hallberg, A. A. Aligia
Summary: This study calculates the charge and spin gaps in the ionic Hubbard chain, considering density-dependent hopping with electron-hole symmetry. The disappearance of the charge (spin) gap indicates a quantum critical point in the charge (spin) sector. Between these critical points, the system behaves as a fully gapped spontaneously dimerized insulator. The study focuses on this region and explores the possibility of an adiabatic Thouless pump with alternating hopping, limited by the size of the gaps.
Article
Multidisciplinary Sciences
Thomas Hartke, Botond Oreg, Carter Turnbaugh, Ningyuan Jia, Martin Zwierlein
Summary: The Hubbard model of attractively interacting fermions is used to study fermion pairing. In this model, a crossover between tightly bound pairs and long-range Cooper pairs occurs, with a pseudo-gap region above the superfluid critical temperature. By directly observing a Hubbard lattice gas of fermionic potassium-40 atoms under a bilayer microscope, the nonlocal nature of fermion pairing is revealed. The study also provides insights into the pseudo-gap behavior in strongly correlated fermion systems.
Article
Physics, Multidisciplinary
Yeyang Zhang, Ryuichi Shindou
Summary: In this study, we propose a mechanism for dissipationless spin-charge conversion using excitonic pseudospin superfluid in an electron-hole double-layer system. By lifting the degeneracy of exciton levels through magnetic exchange fields, we achieve spin-charge coupled superflow.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Yanpeng Qi, Tianping Ying, Xianxin Wu, Zhuoya Dong, Masato Sasase, Qing Zhang, Weiyan Liu, Masaki Ichihara, Yanhang Ma, Jiangping Hu, Hideo Hosono
Summary: The study reports the discovery of an unprecedented vacancy state forming an extended buckled-honeycomb-vacancy (BHV) ordering in Ir16Sb18, which leads to superconductivity by suppressing the BHV ordering. Further theoretical calculations suggest that the buckled structure breaks the crystal inversion symmetry and can mostly suppress the density of states near the Fermi level.
Article
Materials Science, Multidisciplinary
Ryota Nakai, Kentaro Nomura, Yukio Tanaka
Summary: In this study, the Josephson junction of a spin-polarized quantum anomalous Hall insulator with traditional superconductors is investigated, revealing features of equal-spin triplet pairings and confirming characteristics of finite-momentum pairing states. Additionally, in the presence of disorder, the robustness of the chiral edge mode results in high sensitivity of the critical current and equilibrium phase difference to random configurations.
Article
Physics, Multidisciplinary
Woo Chang Chung, Julius de Hond, Jinggang Xiang, Enid Cruz-Colon, Wolfgang Ketterle
Summary: This study explores nonequilibrium spin dynamics in Mott insulator plateaus, observing a resonant effect in spin alignment as lattice depth changes when exchange coupling and on-site anisotropy are similar. The results are supported by many-body numerical simulations and analytical solutions of a two-site model. The research demonstrates the importance of a uniaxial single-ion anisotropy term in stabilizing magnetism for low-dimensional magnetic materials in optical lattices.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Dorsa S. Fartab, Jose Guimaraes, Marcus Schmidt, Haijing Zhang
Summary: This paper investigates the electrostatic doping in p-type tellurium (Te) thin flakes and demonstrates the potential for gate tuning the insulator-metal phase transition and enhancing the Rashba-like spin-orbit coupling using electric double-layer transistors (EDLTs). The study also reveals a crossover from weak localization (WL) to weak antilocalization (WAL), indicating an increased Rashba-like SOC in the material. Moreover, the research shows that the main scattering mechanism in the material is the e-e interaction, and the temperature dependence of the WAL further supports this finding. Remarkably, the ability to control electron spin and enhance the Rashba parameter by a factor of 4 through ionic gating p-type Te is demonstrated, which holds promise for spintronics applications.
Article
Multidisciplinary Sciences
Hanqin Ding, Yan Xu, Weiting Chen
Summary: The one-dimensional antiferromagnetic correlated electron system described by the unusual t-U-J model with alternating on-site interactions at odd and even sites exhibits insulating behavior due to unequal on-site repulsion. Depending on the value of Ue+Uo in relation to 2J, the system can be in a spin-gapped phase with charge-density-wave instability or a spin-gapless phase with coexisting CDW and SDW instabilities.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Physical
W. H. Liu, X. L. Yi, W. C. Li, X. Z. Xing, H. J. Zhao, M. X. Xu, Z. X. Shi
Summary: Based on high quality FeSe1-xSx (0 <= x <= 1) single crystals, the evolution of the mobility spectrum and its relationship with temperature, doping content, and structural factors were investigated. The nonlinear to linear transition of Hall resistivity was attributed to changes in mobility and merging of mobility peaks. The correlation between Tc and carrier density showed weak interaction in the orthogonal phases but a nearly positive correlation in the tetragonal phases. The bond angle and anion height exhibited linear changes with doping content, and their relationship with Tc indicated the importance of structural factors in regulating superconductivity. This research contributes to the understanding of the multi-band and complex phase diagram of iron-based superconductors.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Jin-Ke Bao, Huibo Cao, Matthew J. Krogstad, Keith M. Taddei, Chenfei Shi, Shixun Cao, Saul H. Lapidus, Sander van Smaalen, Duck Young Chung, Mercouri G. Kanatzidis, Stephan Rosenkranz, Omar Chmaissem
Summary: This research utilizes neutron diffraction to elucidate the exact nature of the previously unknown antiferromagnetic ground state of KMn6Bi5 and discovers transverse incommensurate spin density waves for the Mn atoms. The study also reveals a strong real space coupling between charge density waves and spin density waves, and observes a significant magnetoelastic effect during the antiferromagnetic transition.
Article
Physics, Multidisciplinary
Shihao Zhang, Xi Dai, Jianpeng Liu
Summary: In this study, we theoretically investigate correlated insulator states and quantum anomalous Hall states in twisted multilayer graphene systems. We show that these systems can exhibit spin-polarized and valley-polarized insulator states under different interactions, and these states can be manipulated by external forces.
PHYSICAL REVIEW LETTERS
(2022)
Editorial Material
Physics, Multidisciplinary
Xi Dai
CHINESE PHYSICS LETTERS
(2022)
Article
Computer Science, Interdisciplinary Applications
Shiyu Peng, Hongming Weng, Xi Dai
Summary: In this paper, an efficient numerical scheme for multi-band Hubbard models using Gutzwiller method is proposed, which optimizes the total energy to variational determine the ground state and develops an atomic diagonalization method. The results show that the method exhibits fast convergence and efficiency in both inner and outer loops, with better stability and efficiency compared to conventional methods.
COMPUTER PHYSICS COMMUNICATIONS
(2022)
Article
Nanoscience & Nanotechnology
Binghao Guo, Alexander C. C. Lygo, Xi Dai, Susanne Stemmer
Summary: In this study, the observation of a quantum Hall state with a filling factor of zero in a thin film cadmium arsenide sample tuned by a gate voltage is reported, and possible mechanisms underlying this phenomenon are discussed.
Article
Multidisciplinary Sciences
Kaining Yang, Xiang Gao, Yaning Wang, Tongyao Zhang, Yuchen Gao, Xin Lu, Shihao Zhang, Jianpeng Liu, Pingfan Gu, Zhaoping Luo, Runjie Zheng, Shimin Cao, Hanwen Wang, Xingdan Sun, Kenji Watanabe, Takashi Taniguchi, Xiuyan Li, Jing Zhang, Xi Dai, Jian-Hao Chen, Yu Ye, Zheng Han
Summary: The authors report the evidence of unconventional correlated insulating states in bilayer graphene/CrOCl heterostructures and demonstrate their application for low-temperature logic inverters. They investigate the heterostructures based on Bernal-stacked bilayer graphene atop few-layered CrOCl, which exhibit an over-1-G omega-resistance insulating state in a widely accessible gate voltage range. By applying an in-plane electric field, heating, or gating, the insulating state can be switched into a metallic state with an on/off ratio up to 10(7).
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Kaifa Luo, Xi Dai
Summary: We propose a new type of spontaneous symmetry breaking phase caused by softening of the transverse acoustic phonon modes through electron-phonon coupling. These new phases include the shear density wave and self-twisting wave, which are caused by softening of linearly and circularly polarized acoustic phonon modes, respectively. We propose that two of the topological semimetal systems in the quantum limit, where the electrons only occupy the lowest Landau bands under external magnetic field, will be the perfect systems to realize these new phases. Exotic physical effects will be induced in these new phases, including the 3D quantum Hall effect, chiral standing acoustic wave, magnetoacoustic effects, and chiral phonon correction to the Einstein-de Hass effect.
Article
Materials Science, Multidisciplinary
Xiong Fan, Xi Dai
Summary: This paper demonstrates that the WKB quantization rule can be used to analyze the Andreev bound states in nonuniform superconductors. The study considers the effects of nonhomogeneous superconductivity gap functions Delta(x) and other parameters such as the Bogoliubov quasiparticle energy E, Fermi level EF, and total momentum p. Through the application of the WKB method to the Bogoliubov-de Gennes equation, two major results are obtained regarding the determination of the bound states under different conditions.
Article
Materials Science, Multidisciplinary
Hao Shi, Xi Dai
Summary: This paper constructs a heavy fermion representation for twisted bilayer graphene systems, finding two local orbitals that have similar properties to Wannier functions and can be interpreted as zeroth pseudo Landau levels of Dirac fermions. The hybridization between these levels and other itinerant states helps in understanding the electronic states of twisted bilayer graphene.
Article
Materials Science, Multidisciplinary
Xuecong Ji, Jiacheng Gao, Changming Yue, Zhijun Wang, Hua Wu, Xi Dai, Hongming Weng
Summary: In this paper, we theoretically propose that a single layer of CrCl2 (pyrazine) (2) might realize various interaction-driven states based on the quadratic band crossing points (QBCPs) protected by C-4 symmetry. By introducing short-range density-density type repulsion interactions into this system, we have found different phases including the staggered chiral flux state manifesting the quantum anomalous Hall (QAH) effect, the site-nematic insulator, and the site-nematic Dirac semimetal state. The QAH state is robust against perturbations breaking the QBCP but it is weakened by increasing temperature. The tunability of the metal-organic framework by changing the transition-metal elements might improve the gap size and stability of this interaction-induced QAH state.
Article
Materials Science, Multidisciplinary
Song Sun, Hongming Weng, Xi Dai
Summary: This paper proposes that quantized and nearly half-quantized intrinsic anomalous Hall effect can be induced by in-plane external magnetic field through the Zeeman coupling in nonmagnetic 2D systems. The findings are supported by an analytical result from a 2D electron gas model with C3v symmetry and calculations based on a k center dot p Hamiltonian derived from first principle calculations.
Article
Materials Science, Multidisciplinary
Apurva Gaikwad, Song Sun, Peipei Wang, Liyuan Zhang, Jennifer Cano, Xi Dai, Xu Du
Summary: Band structure modulation can drive topological phase transitions, with the Berry phase and Dirac bandgap closing and reopening in ZrTe5 strain-induced topological insulator phase transition directly mapped using quantum oscillations. The impact of strain-tunable spin-dependent Berry phase on the Zeeman effect through quantum oscillation amplitude is critical in modeling quantum oscillations in Dirac bands in topological materials.
COMMUNICATIONS MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Shuai Zhang, Shiyu Peng, Xi Dai, Hongming Weng
Summary: In this study, various nontrivial band topological states were discovered in Chevrel phase materials through first-principle calculations. Compounds with time-reversal symmetry exhibited different topological properties in different phases, and the change of A ions influenced the topological states and other properties.
Article
Materials Science, Multidisciplinary
Tan Zhang, Nicolas Regnault, B. Andrei Bernevig, Xi Dai, Hongming Weng
Summary: We present a two-step method specifically tailored for band structure calculation of small-angle moir??pattern materials. By performing self-consistent field calculations and solving a small number of eigenvalues near the Fermi energy, we accurately obtain the band structures of rigid and corrugated twisted bilayer graphene structures. The method is efficient and applicable to other twisted two-dimensional materials.
Article
Engineering, Electrical & Electronic
Hao Chen, Wei E. Sha, Xi Dai, Yue Yu
Summary: This article provides a digest of electromagnetism theory and a review of the transformation between inertial frames, particularly under low speed limits. It explains the covariant nature of Maxwell's equations using conventional language. The discussions presented clarify why classical electromagnetic theory is inherently relativistic.
PROGRESS IN ELECTROMAGNETICS RESEARCH-PIER
(2022)
Meeting Abstract
Urology & Nephrology
S. Karakus, A. L. Burnett, C. Joseph, X. Dai, D. Hawksworth
JOURNAL OF SEXUAL MEDICINE
(2022)
