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1.
Superconductivity and unconventional density waves in vanadium-based kagome materials AV3Sb5 下载免费PDF全文
Recently, the discovery of vanadium-based kagome metal AV3Sb5 (A= K, Rb, Cs) has attracted great interest in the field of superconductivity due to the coexistence of superconductivity, non-trivial surface state and multiple density waves. In this topical review, we present recent works of superconductivity and unconventional density waves in vanadium-based kagome materials AV3Sb5. We start with the unconventional charge density waves, which are thought to correlate to the time-reversal symmetry-breaking orders and the unconventional anomalous Hall effects in AV3Sb5. Then we discuss the superconductivity and the topological band structure. Next, we review the competition between the superconductivity and charge density waves under different conditions of pressure, chemical doping, thickness, and strains. Finally, the experimental evidence of pseudogap pair density wave is discussed. 相似文献
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In this paper, we consider a viscoelastic wave equation of variable coefficients in the presence of past history with nonlinear damping and delay in the internal feedback and dynamic boundary conditions. Under suitable assumptions, we establish an explicit and general decay rate result without imposing restrictive assumption on the behavior of the relaxation function at infinity by Riemannian geometry method and Lyapunov functional method. 相似文献
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Laterally-coupled ridge-waveguide distributed feedback lasers fabricated without epitaxial regrowth steps have the advantages of process simplification and low cost. We present a laterally coupled grating with slots. The slots etched between the ridge and grating area are designed to suppress the lateral diffusion of carriers and to reduce the influence of the aspect-ratio-dependent-etching effect on the grating morphology in the etching process. Moreover, the grating height in this structure can be decreased to lower the aspect ratio significantly, which is advantageous over the conventional laterally coupled ridge waveguide gratings. The effects of five main structural parameters on the coupling characteristics of gratings are studied by MODE Solutions. It is found that varying the lateral width of the grating can be used as an effective way to tune the coupling strength; narrow slots (100 nm and 300 nm) and wide ridge (2 μm-4 μm) promote the stability of grating coupling coefficient and device performance. It is important to note that the grating bottom should be fabricated precisely. The comparative study of carrier distribution and mode field distribution shows that the introduction of narrow slots can strengthen the competitive advantage and stability of the fundamental mode. 相似文献
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We investigate a (2+1)-dimensional shallow water wave equation and describe its nonlinear dynamical behaviors in physics. Based on the N-soliton solutions, the higher-order fissionable and fusionable waves, fissionable or fusionable waves mixed with soliton molecular and breather waves can be obtained by various constraints of special parameters. At the same time, by the long wave limit method, the interaction waves between fissionable or fusionable waves with higher-order lumps are acquired. Combined with the dynamic figures of the waves, the properties of the solution are deeply studied to reveal the physical significance of the waves. 相似文献
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High dielectric loss materials have an important application in electromagnetic (EM) absorption fields. In this paper, the ternary nanocomposites: 1T/2H-MoS2/Mo2S3 with heterogeneous interfaces are synthesized by hydrothermal method. XRD, XPS, FTIR, SEM, and TEM measurements are applied to study the structure, morphology, and composition. The frequency spectra of complex permittivity (εr-f) are measured in 2–18 GHz by vector network analyzer. The results show that the nanocomposites have higher dielectric loss angle tangents than the reported 2H-MoS2 absorbers. Based on the εr-f spectra, the reflection loss-frequency curves () are simulated at given thicknesses. An effective absorption bandwidth of 5.2 GHz (12.8–18 GHz) and a peak of −29.49 dB are achieved in a thin thickness of 1.62 mm, which are comparable to the reported 2H-MoS2 absorbers with complex composition, showing that the 1T/2H-MoS2/Mo2S3 nanocomposites have great application potential as an EM wave absorber in the Ku band. 相似文献
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Asymmetric mode transformation in waveguide is of great significance for on-chip integrated devices with one-way effect, while it is challenging to achieve asymmetric nonlinear-mode-conversion (NMC) due to the limitations imposed by phase-matching. In this work, we theoretically proposed a new scheme for realizing asymmetric NMC by combining frequency-doubling process and periodic PT symmetric modulation in an optical waveguide. By engineering the one-way momentum from PT symmetric modulation, we have demonstrated the unidirectional conversion from pump to second harmonic with desired guided modes. Our findings offer new opportunities for manipulating nonlinear optical fields with PT symmetry, which could further boost more exploration on on-chip nonlinear devices assisted by non-Hermitian optics. 相似文献
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Relationship between the spatial position of the seed and growth mode for single-crystal diamond grown with an enclosed-type holder 下载免费PDF全文
Wen-Liang Xie 《中国物理 B》2022,31(10):108106-108106
The relationship between the spatial position of the diamond seed and growth mode is investigated with an enclosed-type holder for single-crystal diamond growth using the microwave plasma chemical vapor deposition epitaxial method. The results demonstrate that there are three main regions by varying the spatial position of the seed. Due to the plasma concentration occurring at the seed edge, a larger depth is beneficial to transfer the plasma to the holder surface and suppress the polycrystalline diamond rim around the seed edge. However, the plasma density at the edge decreases drastically when the depth is too large, resulting in the growth of a vicinal grain plane and the reduction of surface area. By adopting an appropriate spatial location, the size of single-crystal diamond can be increased from 7 mm × 7 mm × 0.35 mm to 8.6 mm × 8.6 mm × 2.8 mm without the polycrystalline diamond rim. 相似文献