Article
Multidisciplinary Sciences
Jiangxu Li, Jiaxi Liu, Stanley A. Baronett, Mingfeng Liu, Lei Wang, Ronghan Li, Yun Chen, Dianzhong Li, Qiang Zhu, Xing-Qiu Chen
Summary: Researchers have discovered over 5000 topological phononic (TP) materials through a high-throughput screening and data-driven approach, revealing the mechanisms of their occurrence in various materials, including Weyl and nodal-line types. The discovery of these materials opens up new possibilities for exploring their structure-property relationships and designing devices related to TPs in the future.
NATURE COMMUNICATIONS
(2021)
Article
Multidisciplinary Sciences
Yoshiyuki Ohtsubo, Toru Nakaya, Takuto Nakamura, Patrick Le Fevre, Francois Bertran, Fumitoshi Iga, Shin-Ichi Kimura
Summary: The breakdown of in-plane rotation symmetry in topological surface states (TSSs) of SmB6 is shown to be related to the importance of surface atomic structure. Experimentally, it is found that TSSs are anisotropic and lack the fourfold rotation symmetry observed in the bulk on the SmB6(001)-p(2 x 2) surface. These results suggest that engineering the surface atomic structure could provide a new pathway to tailor various properties of TSSs.
NATURE COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Robert Peters, Kazuhiro Kimura, Yoshihiro Michishita, Tsuneya Yoshida, Norio Kawakami
Summary: The study highlights the emergence of exceptional points and nontrivial spin textures on the surface of a topological Kondo insulator, along with the creation of long-lifetime quasiparticle states through non-Hermitian effects. Additionally, it explores how non-Hermiticity alters the spin texture of surface states and demonstrates the impact of non-Hermitian effects on the eigenstates and eigenvalues of correlated materials.
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
Physics, Applied
Y. Sato, Z. Xiang, Y. Kasahara, S. Kasahara, L. Chen, C. Tinsman, F. Iga, J. Singleton, N. L. Nair, N. Maksimovic, J. G. Analytis, Lu Li, Y. Matsuda
Summary: Recent studies on Kondo insulators, such as YbB12, have shown that the transport properties exhibit insulating behavior at high temperatures and a plateau at low temperatures, with the plateau value decreasing with decreasing sample thickness. Additionally, weak-antilocalization effects were observed in the magnetoresistance of microstructures, indicating the presence of a topologically protected surface state. High-field resistivity measurements further support the occurrence of quantum oscillations in the insulating bulk of YbB12.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Review
Multidisciplinary Sciences
Xiujuan Zhang, Farzad Zangeneh-Nejad, Ze-Guo Chen, Ming-Hui Lu, Johan Christensen
Summary: Light and sound are widely studied as classical waves, but they have recently been connected to exotic topological phases of matter. This has sparked a new wave of research, going beyond conventional topological systems and exploring non-linear, non-Hermitian, and non-Abelian topology, as well as topological defects. This article provides an overview of the current state of research and explores future directions for valuable applications.
Article
Multidisciplinary Sciences
Alexander J. Breindel, Yuhang Deng, Camilla M. Moir, Yuankan Fang, Sheng Ran, Hongbo Lou, Shubin Li, Qiaoshi Zeng, Lei Shu, Christian T. Wolowiec, Ivan K. Schuller, Priscila F. S. Rosa, Zachary Fisk, John Singleton, M. Brian Maple
Summary: This article reports the study of the conductive surface state (CSS) and bulk phase properties of FeSi, and finds that a CSS exists below 19K. Comparison with the Kondo insulator SmB6 reveals similar behavior in magnetoresistance and energy gap changes between the two materials.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Optics
Kai-Ye Shi, Rui-Qi Chen, Shuaining Zhang, Wei Zhang
Summary: In this paper, a scheme is proposed to fully characterize Floquet topological phases using bulk dispersions and a set of topological invariants associated with the band-touching points.
Article
Materials Science, Multidisciplinary
Xinying Li, Ning Mao, Runhan Li, Ying Dai, Baibiao Huang, Chengwang Niu
Summary: In this study, a topological switch between normal insulator and AFM TI in two-dimensional NaMnBi quintuple layers is theoretically demonstrated. Using first-principles calculations, the researchers investigated the structure, stability, magnetism, and electronic properties, showing that the band gap and topology can be effectively tuned. The results not only expand the understanding of magnetic topological states but also propose potential applications in topological AFM spintronics.
JOURNAL OF MATERIALS CHEMISTRY C
(2021)
Article
Physics, Multidisciplinary
Gal Shavit, Yuval Oreg
Summary: In this Letter, we investigate interacting systems with spontaneous discrete symmetry breaking and find that the degenerate symmetry-broken states are topologically distinct gapped phases. Edge modes emerge at the interfaces between the two topological phases. By introducing a weak disorder field related to the order parameter, we observe a thermal transition from a gapped uniform phase to a phase with disorder-induced domain structure driven by the entropy of the edge modes. We describe this transition using a phenomenological Landau functional and validate our findings with a specific microscopic model. Furthermore, we discuss the potential experimental manifestations of this phase transition and suggest graphene-based moiré heterostructures as promising materials for detecting such transitions.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Dongwook Kim, Feng Liu
Summary: In this study, we systematically investigate the evolution of the band gap in a topological alloy as a function of alloy concentration using first-principles calculations. We found that the band gap in topological alloys exhibits a complex fragmented pattern and shows a linear dependence on concentration locally in each distinct phase. Moreover, we demonstrate that topological alloy engineering can be used as a general approach to tune the topological order.
Article
Multidisciplinary Sciences
Milad Jangjan, Mir Vahid Hosseini
Summary: A new kind of topological phase transition has been theoretically reported, where the closing-reopening of bandgap is accompanied by passing the Fermi level through an additional band. The resulting nontrivial topological metal phase is characterized by stable zero-energy localized edge states existing within the full gapless bulk states, protected by hidden inversion symmetry. Other required symmetries such as chiral, particle-hole, or full inversion symmetry are absent in the system.
SCIENTIFIC REPORTS
(2021)
Article
Quantum Science & Technology
Jonghoon Kim, Kwangsik Jeong, Hanbum Park, Seokbo Hong, Dajung Kim, Gihwan Nam, Seungwon Rho, Hee Jun Shin, Chul Kang, Mann-Ho Cho
Summary: In this work, the suppression of surface properties in Bi2Se3 of various thicknesses grown on antiferromagnetic NiO, which has a strong exchange interaction is investigated. The study found that under perpendicular magnetic fields, a drastic decrease in mobility mu and in the number of phase coherent channels alpha in 5 QL Bi2Se3 on NiO are observed. Additionally, the THz transmission study shows that an increase in the surface penetration depth xi can accelerate the hybridization of surface states, which is also verified using the optical pump THz probe. This rapid collapse of surface states indicates the unique role of antiferromagnetic materials in band overlap, suggesting that the topological surface nature can be modulated by forming an antiferromagnet-topological insulator heterostructure.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Chemistry, Physical
Aiyun Luo, Zhida Song, Gang Xu
Summary: By using first-principles calculations and magnetic topological quantum chemistry, this study reveals the presence of fragile topological electronic states in the antiferromagnetic monolayer FeSe, which is very close to an antiferromagnetic topological insulator with robust edge states. These fragile topological states are captured by a double-degenerate nearly flat band just below the Fermi level. The S-4z symmetry is found to protect this fragile topology, leading to a 2D second-order topological insulator that supports a bound state with fractional charge e/2 at the corner of the sample. This work provides an important platform for studying the intriguing properties of magnetic fragile topological electronic states and can explain previous observations in the checkerboard antiferromagnetic monolayer FeSe.
NPJ COMPUTATIONAL MATERIALS
(2022)
Article
Physics, Applied
Weipeng Hu, Chao Liu, Jun Guo, Xiaoyu Dai, Shuangchun Wen, Yuanjiang Xiang
Summary: This study proposes a high-efficiency second-harmonic generation (SHG) using dual-frequency topological edge states (TESs) in topological photonic crystals (TPCs) with slow-light conditions. The wave vector matching and energy conservation conditions are achieved by adjusting the structural parameters of TPCs. The double-resonant nonlinear interaction between two TESs is enabled using a square lattice TPC. The topological localization of TESs and the long interaction time of the slow-light effect significantly increase the energy densities of the fundamental wave and SHG.
JOURNAL OF APPLIED PHYSICS
(2023)