Article
Materials Science, Multidisciplinary
Alexis Morvan, Mathieu Fechant, Gianluca Aiello, Julien Gabelli, Jerome Esteve
Summary: Honeycomb lattices for microwave photons with frequency imbalance show topological valley edge states at the interface between lattices with opposite imbalance. The spatial dependence of modes along the interface is imaged to obtain the dispersion relation, which is compared to predictions of an ab initio tight-binding model for the microwave photonic lattices.
OPTICAL MATERIALS EXPRESS
(2021)
Article
Materials Science, Multidisciplinary
Kwang-Hyon Kim, Kwang-Kwon Om
Summary: This study demonstrates the observation of multiband photonic topological valley-Hall edge states and second-order corner states in square lattice photonic crystals consisting of triangular dielectric rods, offering important implications for the realization of photonic nano-resonators and nonlinear topological frequency conversion.
ADVANCED OPTICAL MATERIALS
(2021)
Article
Optics
Guochao Wei, Zhenzhen Liu, Licheng Wang, Jianyuan Song, Jun-Jun Xiao
Summary: This study demonstrates the existence of topological valley and pseudo-spin edge states in a carefully designed two-dimensional Kekule photonic crystal with time reversal symmetry. The presence of these edge states was confirmed through theoretical, numerical, and experimental analysis, and their distinct characteristics were identified through transmission measurements and end-scattering analysis.
PHOTONICS RESEARCH
(2022)
Article
Chemistry, Multidisciplinary
Jingwen Ma, Xiang Xi, Xiankai Sun
Summary: An integrated nano-electromechanical valley-Hall topological insulator operating in the very-high-frequency regime has been experimentally realized, demonstrating backscattering-immune valley kink states in the fundamental and second-order frequency bands. The results not only enable various applications in very-high-frequency integrated phononic circuits with enhanced robustness and capacity, but also open the door to experimental exploration of mechanical nonlinearities in topologically nontrivial nanostructures involving fundamental and second-order frequencies.
ADVANCED MATERIALS
(2021)
Article
Physics, Condensed Matter
Yibao Dong, Yuanbo Wang, Changlin Ding, Shilong Zhai, Xiaopeng Zhao
Summary: A tunable acoustic topological insulator (ATI) with valley-projected edge states is proposed and engineered using a metamaterial structure, demonstrating robust edge sound transport and flexible manipulation of sound propagation paths. Theoretical analysis, numerical simulation, and experimental measurement confirm the existence of edge states, enriching the design of ATIs with tunability and offering potential applications in flexible manipulation of sound propagation.
PHYSICA B-CONDENSED MATTER
(2021)
Article
Chemistry, Multidisciplinary
Runhan Li, Ning Mao, Xinming Wu, Baibiao Huang, Ying Dai, Chengwang Niu
Summary: This study proposes the emergence of robust magnetic topological insulators in two-dimensional ferromagnets, regardless of magnetization directions. The 2H-RuCl2 and Janus VSSe monolayers are identified as experimentally feasible candidates of such insulators. It is also found that the valley polarization of SOTIs can be significantly greater than that of known ferrovalley materials under out-of-plane magnetization.
Article
Chemistry, Multidisciplinary
Peng Li, Jinjun Ding, Steven S-L Zhang, James Kally, Timothy Pillsbury, Olle G. Heinonen, Gaurab Rimal, Chong Bi, August DeMann, Stuart B. Field, Weigang Wang, Jinke Tang, Jidong Samuel Jiang, Axel Hoffmann, Nitin Samarth, Mingzhong Wu
Summary: This study reports a genuine topological Hall effect in a TI/MI structure, where the contribution of skyrmions to the Hall effect outweighs the coexistence of magnetic phases.
Article
Physics, Applied
Zichong Yue, Danwei Liao, Zhiwang Zhang, Wei Xiong, Ying Cheng, Xiaojun Liu
Summary: The study experimentally demonstrates a reconfigurable condensed acoustic second-order topological insulator and successfully observes the appearance of topological corner states in finite structures.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Xin Yang, Yanqing Shen, Jiajia Liu, Lingling Lv, Min Zhou, Yu Zhang, Xianghui Meng, Zhongxiang Zhou, Yangdong Zheng
Summary: The topologically nontrivial phase and quantum anomalous Hall (QAH) effect were predicted in the ferromagnetic non-Dirac half-metal N2Pd4S6 monolayer using first-principles calculations. The N2Pd4S6 monolayer prefers out-of-plane magnetization and exhibits a Curie temperature of similar to 80 K due to dual double-exchange interaction. The introduction of magnetic exchange and spin-orbit coupling enables the realization of the topologically nontrivial phase and QAH state, as well as the unique quantum anomalous valley Hall (QAVH) effect induced by compressive strain.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Lei Liu, Bao Zhao, Jiayong Zhang, Hairui Bao, Hao Huan, Yang Xue, Yue Li, Zhongqin Yang
Summary: By constructing a breathing kagome-honeycomb lattice, the study investigated the electronic states and evolution of Dirac cones in metal-organic frameworks, revealing coexistence of multiple Hall effects. A material platform for potential applications in valleytronics, electronics, and spintronics was proposed based on the findings.
Article
Engineering, Mechanical
Xiangzhen Han, Li Li, Chaosheng Mei, Yujin Hu, Xuelin Wang
Summary: This study proposes an acoustic source localization method based on acoustic valley-Hall topological insulators (VHTIs), which uses a thin film to improve directional sound reception and decrease the half-power beamwidth.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Physics, Applied
Zhenyu Wang, Yuzhen Yang, Houyin Li, Han Jia, Jinlong Luo, Jian Huang, Zhennan Wang, Bo Jiang, Ningjing Yang, Guojun Jin, Hai Yang
Summary: This study focuses on the acoustic valley interface states, constructing a two-dimensional triangular-lattice phononic crystal with C-3v-symmetric scatterers to achieve acoustic valley Hall topological insulators. Through numerical calculations and experimental integration, successful implementation of multichannel acoustic communication devices for topological transport has been achieved.
PHYSICAL REVIEW APPLIED
(2021)
Article
Physics, Multidisciplinary
Hu Jun-Rong, Kong Peng, Bi Ren-Gui, Deng Ke, Zhao He-Ping
Summary: This paper numerically studies a two-dimensional acoustic honeycomb structure with a triangle resonant cavity and constructs a second-order topological insulator by inducing topological phase transition. The topological properties of the second-order topological insulator are characterized using quantized quadrupole moments. Gapped zero-dimensional corner states are observed in both triangular and hexagonal structures, but only the corner states in the hexagonal structure exhibit robustness.
ACTA PHYSICA SINICA
(2022)
Article
Nanoscience & Nanotechnology
Boquan Ren, Hongguang Wang, Victor O. Kompanets, Yaroslav Kartashov, Yongdong Li, Yiqi Zhang
Summary: This study investigates topological edge solitons propagating along the edge of a photonic topological insulator, predicting the formation of dark valley Hall edge solitons at domain walls between two honeycomb lattices. These dark solitons are exceptionally robust, do not require external magnetic fields, and can circumvent sharp corners. Analytically constructed envelope equations show their long-distance stability and repulsive interactions, leading to the formation of two gray edge solitons. These results suggest that nonlinear valley Hall systems can support a variety of self-sustained topological states in different systems.
Article
Physics, Multidisciplinary
Li-Yang Zheng, Johan Christensen
Summary: The study demonstrates an acoustic 3D honeycomb lattice featuring several Dirac cones, leading to different orders of topological insulator properties. By analyzing the topological origin of surface, hinge, and corner states, new routes for controlling sound and vibration are offered.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Jingjing Liu, Zhengwei Li, Yujiang Ding, An Chen, Bin Liang, Jing Yang, Jian-Chun Cheng, Johan Christensen
Summary: This article introduces an ultrasonic motor based on a meta engine block that can convert the linear momentum of sound into orbital angular momentum. By optimizing the design and adjusting the boundary conditions, efficient excitation of the desired angular momentum is achieved, enabling noninvasive driving of the ultrasonic motor.
ADVANCED MATERIALS
(2022)
Article
Physics, Applied
Danwei Liao, Zichong Yue, Zhiwang Zhang, Hai-Xiao Wang, Ying Cheng, Xiaojun Liu
Summary: This study establishes the connection between acoustic Tamm mode and typical topological acoustic mode, and observes the existence and variation of Tamm edge modes and Tamm corner modes through experimental and numerical simulations. The findings are significant for the development of acoustic functional devices.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Multidisciplinary
Zichong Yue, Zhiwang Zhang, Hai-Xiao Wang, Wei Xiong, Ying Cheng, Xiaojun Liu
Summary: Research on the application of higher-order topological insulators in acoustic systems is highly significant. This study proposes a new design scheme for acoustic SOTIs and observes the state switching process experimentally. The results demonstrate the robustness of topological corner states in the presence of defects.
NEW JOURNAL OF PHYSICS
(2022)
Article
Multidisciplinary Sciences
Zhiwang Zhang, Penglin Gao, Wenjie Liu, Zichong Yue, Ying Cheng, Xiaojun Liu, Johan Christensen
Summary: The authors engineer an artificial honeycomb lattice in single-wall carbon nanotubes and explore their topological features for sound. They find that armchair tubes remain gapless while the zigzag counterparts host nontrivial edge states. The structured tubular lattice symmetry remains intact, and its nontrivial phase is governed by the chirality and the tube diameter. This research has broad implications for various fields such as acoustics, photonics, mechanics, and electronics.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Rene Pernas-Salomon, Li-Yang Zheng, Zhiwang Zhang, Penglin Gao, Xiaojun Liu, Ying Cheng, Johan Christensen
Summary: This article introduces the research progress in thermoacoustic topological materials, which constructs acoustic lattices coated with electrically biased carbon nanotube films. It investigates the influence of geometry and acoustic gain on acoustic interactions.
NPJ COMPUTATIONAL MATERIALS
(2022)
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
Nanoscience & Nanotechnology
J. Feilhauer, M. Zelent, Zhiwang Zhang, J. Christensen, M. Mruczkiewicz
Summary: We demonstrate a numerical simulation of magnonic crystals with unidirectional, topologically protected edge states. The crystal is composed of dipolarly coupled Permalloy triangles, and we show that the structure can be scaled up due to its geometry. Edge states can be found over a wide frequency range, and experimental detection can be done using state-of-the-art techniques. We present a proof-of-concept magnonic Chern topological insulator nanostructure with a simple geometry feasible for experimental realization. Additionally, we demonstrate a magnonic switch by inducing a topological phase transition that changes the direction of the topological edge state.
Article
Physics, Applied
Taimin Wang, Chun Gong, Suying Zhang, Yuanzhou Zhu, Houyou Long, Ying Cheng, Xiaojun Liu
Summary: Emerging artificial acoustically soft boundaries (ASBs) have great potential for sound absorptive devices. However, current ASBs have narrow-band limitations that require stringent matching of resonant characteristics. This study proposes a method to construct a broadband ASB (BASB) by coupling two multi-band ASBs using coiled space resonators (CSRs), achieving ultra-broadband absorption.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Chen Liu, Zhiwang Zhang, Danwei Liao, Zichong Yue, Chengrong Ma, Ying Cheng, Xiaojun Liu
Summary: Over the recent decade, topological insulators have become a focus of research in the field of acoustics due to their unique properties for manipulating wave propagation. However, most studies currently are reported in a complex context, and it is still a challenge to achieve efficient acoustic rainbow trapping in a straightforward setup.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Multidisciplinary
Bolun Hu, Zhiwang Zhang, Zichong Yue, Danwei Liao, Yimin Liu, Haixiao Zhang, Ying Cheng, Xiaojun Liu, Johan Christensen
Summary: The Su-Schrieffer-Heeger (SSH) model is a fundamental framework in condensed-matter topology, specifically for studying spinless electrons in chains with staggered bonds. The chiral symmetry of this model ensures the existence of surface states at zero energy within the energy gap. Symmetry plays a crucial role in artificial materials subjected to parity and time-reversal operations. In this study, we introduce the concept of anti-PT (APT) symmetric systems in an acoustic SSH lattice with gain and loss components. Our experiments demonstrate the importance of non-Hermitian phase in the topological defect states, where broken symmetry suppresses them and intact PT or APT symmetry leads to damped or evanescent decay, respectively.
PHYSICAL REVIEW LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Fangfang Ju, Chen Liu, Ying Cheng, Shengyou Qian, Xiaojun Liu
Summary: This study extends parity-time symmetric systems to acoustics by using coupled Mie resonators, achieving PT symmetry with only passive materials. Coherent perfect absorption is observed in the PT symmetric phase, showcasing potential applications in tunable noise control and acoustic modulators.
Article
Materials Science, Multidisciplinary
Maria Rosendo Lopez, Zhiwang Zhang, Daniel Torrent, Johan Christensen
Summary: Rotating overlapping lattices leads to moire interference patterns and correlated superconductivity in twisted bilayer graphene. This study employs a sound wave expansion technique to mimic this physics and designs moire sound interference characteristics in holey bilayer plates.
COMMUNICATIONS MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Penglin Gao, Yegao Qu, Johan Christensen
Summary: This research has identified stable unidirectional Rayleigh surface waves in active materials, which exhibit non-reciprocal and non-Hermitian characteristics, unlike waves in passive solids. These findings may open up new possibilities for manipulating elastic waves in unconventional ways.
COMMUNICATIONS MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Danwei Liao, Zhiwang Zhang, Ying Cheng, Xiaojun Liu
Summary: This study proposes a subwavelength acoustic third-order topological insulator based on the theoretical framework of acoustic transmission lines, which enables the engineering of acoustic negative couplings to achieve topological corner states. The occurrence of these states in both the 3D Su-Schrieffer-Heeger (SSH) model and the octupole insulator is validated through topological invariant calculations and numerical simulations in analogous acoustic networks.
