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849 results on '"Fan, Haiyan"'

6. Analytical Method for Metasurface-Based Cloaking Under Arbitrary Oblique Illumination

Author

Zhang, Yi, Fan, Haiyan, Zhang, Yujie, Ran, Lixin, Ye, Dexin, and Chen, Xudong

Subjects
Physics - Optics, Physics - Computational Physics
Abstract

The performance of antennas can severely deteriorate in the presence of adjacent electrically-large scatterers. In this work, we use a conducting hollow cylinder to shield the scatterer. The cylinder is shelled with single layer dielectric and electromagnetic metasurface. The scattering field analysis with respect to the surface impedance is derived. By optimizing the anisotropic impedance distribution, the scattering cross-section can be effectively reduced. The proposed method is valid for both TMz, TEz and non-TM/TE incident field. The accuracy and effectiveness of the method are verified by four cloaking scenarios in microwave regime. We demonstrate that with the surface impedance obtained by our method, a metasurface is designed with physical subwavelength structure. We also show a cloaking scenario under magnetic dipole radiation, which is closer to the case of a realistic antenna. This method can be further applied to cloaking tasks in terahertz and optical regimes., Comment: 16 pages, 10 figures

Published
2023

25. Topological phononics arising from fluid-solid interactions

Author

Wu, Xiaoxiao, Fan, Haiyan, Liu, Tuo, Gu, Zhongming, Zhang, Ruo-Yang, Zhu, Jie, and Zhang, Xiang

Abstract

Nontrivial band topologies have been discovered in classical systems and hold great potential for device applications. Unlike photons, sound has fundamentally different dynamics and symmetries in fluids and solids, represented as scalar and vector fields, respectively. So far, searches for topological phononic materials have only concerned sound in either fluids or solids alone, overlooking their intricate interactions in "mixtures". Here, we report an approach for topological phononics employing such unique interplay, and demonstrate the realization of type-II nodal rings, elusive in phononics, in a simple three-dimensional phononic crystal. Type-II nodal rings, as line degeneracies in momentum space with exotic properties from strong tilting, are directly observed through ultrasonic near-field scanning. Strongly tilted drumhead surface states, the hallmark phenomena, are also experimentally demonstrated. This phononic approach opens a door to explore topological physics in classical systems, which is easy to implement that can be used for designing high-performance acoustic devices.

Published
2022

36. Pseudospin-valley-coupled phononic topological insulator with edge and corner states

Author

Fan, Haiyan, Xia, Baizhan, Zheng, Shengjie, and Tong, Liang

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Applied Physics
Abstract

Topologically protected gapless edge states are phases of quantum matter which behave as massless Dirac fermions, immunizing against disorders and continuous perturbations. Recently, a new class of topological insulators (TIs) with topological corner states have been theoretically predicted in electric systems, and experimentally realized in two-dimensional (2D) mechanical and electromagnetic systems, electrical circuits, optical and sonic crystals, and elastic phononic plates. Here, we demonstrate a pseudospin-valley-coupled phononic TI, which simultaneously exhibits gapped edge states and topological corner states. Pseudospin-orbit coupling edge states and valley-polarized edge state are respectively induced by the lattice deformation and the symmetry breaking. When both of them coexist, these topological edge states will be greatly gapped and the topological corner state emerges. Under direct field measurements, the robust edge propagation behaving as an elastic waveguide and the topological corner mode working as a robust localized resonance are experimentally confirmed. The pseudospin-valley coupling in our phononic TIs can be well-controlled which provides a reconfigurable platform for the multiple edge and corner states, and exhibits well applications in the topological elastic energy recovery and the highly sensitive sensing., Comment: 18 pages, 5 figures

Published
2019

42. Elastic higher-order topological insulator with topologically protected corner states

Author

Fan, Haiyan, Xia, Baizhan, Tong, Liang, Zheng, Shengjie, and Yu, Dejie

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

Topologically gapless edge states, characterized by topological invariants and Berry's phases of bulk energy bands, provide amazing techniques to robustly control the reflectionless propagation of electrons, photons and phonons. Recently, a new family of topological phases, dictated by the bulk polarization, has been observed, leading to the discovery of the higher-order topological insulators (HOTIs). So far, the HOTIs are only demonstrated in discrete mechanical and electromagnetic systems and electrical circuits with the quantized quadrupole polarization. Here, we realize the higher-order topological states in a two-dimensional (2D) continuous elastic system whose energy bands can be well described. We experimentally observe the gapped one-dimensional (1D) edge states, the trivially gapped zero-dimensional (0D) corner states and the topologically protected 0D corner states. Compared with the trivial corner modes, the topological ones, immunizing against defects, are robustly localized at the obtuse-angled but not the acute-angled corners. The topological shape-dependent corner states open a new route for the design of the topologically-protected but reconfigurable 0D local eigenmodes and provide an excellent platform for the topological transformation of elastic energy among 2D bulk, 1D edge and 0D corner modes., Comment: 10 pages,5 figures

Published
2018
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50. Tailoring Electrode–Electrolyte Interface Using an Electron‐Deficient Borate‐Based Additive in MgTFSI2‐MgCl2/DME Electrolyte for Rechargeable Magnesium Batteries.

Author

Fan, Haiyan, Zhang, Xinxin, Xiao, Jianhua, Chen, Wenjie, Lin, Qiyuan, Ng, Zi Shyun, Lin, Yitao, Su, Yi, Pan, Ludi, Su, Yipeng, Ren, Shuaiyang, Liu, Haowen, Li, Xuanzhang, and Zhang, Yuegang

Subjects
SOLID electrolytes, PHOTOELECTRON spectroscopy, DENSITY functional theory, DYNAMIC simulation, ELECTROLYTES
Abstract

Rechargeable magnesium metal batteries need an electrolyte that forms a stable and ionically conductive solid electrolyte interphase (SEI) on the anodes. Here, we used molecular dynamic simulation, density functional theory calculation, and X‐ray photoelectron spectroscopy analysis to investigate the solvation structures and SEI compositions in electrolytes consisting of dual‐salts, magnesium bis(trifluoromethanesulfonyl)imide (MgTFSI2), and MgCl2, with different additives in 1,2‐dimethoxyethane (DME) solvent. We found that the formed [Mg3(μ‐Cl)4(DME)mTFSI2] (m = 3, 5) inner‐shell solvation clusters in MgTFSI2‐MgCl2/DME electrolyte could easily decompose and form a MgO‐ and MgF2‐rich SEI. Such electron‐rich inorganic species in the SEI, especially MgF2, turned out to be detrimental for Mg plating/stripping. To reduce the MgF2 and MgO contents in SEI, we introduce an electron‐deficient tri(2,2,2‐trifluoroethyl) borate (TFEB) additive in the electrolyte. Mg//Mg cells using the MgTFSI2‐MgCl2/DME‐TFEB electrolyte could cycle stably for over 400 h with a small polarization voltage of ~150 mV. Even with the presence of 800 ppm H2O, the electrolyte with TFEB additive could still preserve its good electrochemical performance. The optimized electrolyte also enabled stable cycling and high‐rate capability for Mg//Mo6S8 and Mg//CuS full cells, showing great potential for future applications. [ABSTRACT FROM AUTHOR]

Published
2024
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