Surface plasmon polaritons in topological insulator

We study surface plasmon polaritons on topological insulator-vacuum interface. When the time-reversal symmetry is broken due to ferromagnetic coupling, the surface states exhibit magneto-optical Kerr effect. This effect gives rise to a novel transverse type surface plasmon polariton, besides the longitudinal type. In specific, these two types contain three different channels, corresponding to the pole of determinant of Fresnel reflection matrix. All three channels of surface plasmon polaritons display tight confinement, long lifetime and show strong light-matter coupling with a dipole emitter.Comment: 6 pages, 4 figure

Omnia Juncta in Uno*: foreign powers and trademark protection in Shanghai's concession era

We investigate how firms and markets adapt to trademark protection, an extensively used but under-examined form of IP protection to address asymmetric information, by exploring a historical precedent: China's trademark law of 1923. Exploiting unique, newly digitized firm-employee and firm-agent datasets from Shanghai in 1872-1941, we show that the trademark law, established as an unanticipated and Western-disapproved response to end foreign privileges in China, shaped firm dynamics and relationships on all sides of trade-mark conflicts. Western firms with greater dependence on trademark protection grew and raised brand investment, while Japanese businesses, most frequently accused of counterfeiting, contracted despite attempts to build their own brands. The trademark law also fostered relationships with domestic intermediaries, both within and outside the boundaries of Western firms, and the growth of the Chinese intermediary sector. At the market level, the trademark law did not reduce competition or raise brand prices, leading to a coexistence of trademarks and competitive markets and ultimately gains in consumer welfare. A comparison with previous attempts by foreign powers-such as extraterritorial rights and bilateral treaties-shows that the alternative institutions were broadly unsuccessful. *Omnia Juncta in Uno ("All Joined in One") was the Latin motto on the municipal seal of the Shanghai International Settlement (1843-1941) and signified the joint governance of foreign powers in the settlement

The Couplings of Rock/Carbonate Groundwater/Cement Leachate

Hyper-alkaline cement leachates generated from the cement buffer of a nuclear waste disposal site have significant influences on the mineralogy of the host rock, creating a chemically disturbed zone (CDZ). Three major types of cement leachates are formed during the evolution process. Most of the existing scenario modelling research has been focused on the influence of the cement leachate on the host rock. However, the influence of the groundwater in the host rock on the evolution of the CDZ remains unexplored. This paper presents a numerical scenario modelling of the couplings among carbonate groundwater, cement leachates and rock minerals. The results reveal that the high carbonate groundwater significantly affects the precipitation of calcium silicate hydrate (C-S-H) and calcite, and consequently alters the physical and chemical properties of the host rock. This finding provides an essential guide for selection of the location of geological disposal facility (GDF) in terms of the groundwater chemistry

Scanning tunneling microscopy study of the possible topological surface states in BiTeCl

Recently, the non-centrosymmetric bismuth tellurohalides such as BiTeCl are being studied as possible candidates of topological insulators. While some photoemission studies showed that BiTeCl is an inversion asymmetric topological insulator, others showed that it is a normal semiconductor with Rashba splitting. Meanwhile, first-principle calculationsfailed to confirm the existence of topological surface states in BiTeCl so far. Therefore, the topological nature of BiTeCl requires further investigation. Here we report low temperature scanning tunneling microscopy study on the surface states of BiTeCl single crystals. On the tellurium-terminated surfaces with low defect density, strong evidences for topological surface states are found in the quasi-particle interference patterns generated by the scattering of these states, both in the anisotropy of the scattering vectors and the fast decay of the interference near step edges. Meanwhile, on samples with much higher defect densities, we observed surface states that behave differently. Our results help to resolve the current controversy on the topological nature of BiTeCl.Comment: 13pages,4figure

Phase Structure of the Topological Anderson Insulator

We study the disordered topological Anderson insulator in a 2-D (square not strip) geometry. We first report the phase diagram of finite systems and then study the evolution of phase boundaries when the system size is increased to a very large $1120 \times 1120$ area. We establish that conductance quantization can occur without a bulk band gap, and that there are two distinct scaling regions with quantized conductance: TAI-I with a bulk band gap, and TAI-II with localized bulk states. We show that there is no intervening insulating phase between the bulk conduction phase and the TAI-I and TAI-II scaling regions, and that there is no metallic phase at the transition between the quantized and insulating phases. Centered near the quantized-insulating transition there are very broad peaks in the eigenstate size and fractal dimension $d_2$; in a large portion of the conductance plateau eigenstates grow when the disorder strength is increased. The fractal dimension at the peak maximum is $d_2 \approx 1.5$. Effective medium theory (CPA, SCBA) predicts well the boundaries and interior of the gapped TAI-I scaling region, but fails to predict all boundaries save one of the ungapped TAI-II scaling region. We report conductance distributions near several phase transitions and compare them with critical conductance distributions for well-known models.Comment: Minor changes only in this versio

Formation of robust and completely tunable resonant photonic band gaps

We identify different types of the photonic band gaps (PBGs) of two dimensional magnetic photonic crystals (MPCs) consisting of arrays of magnetic cylinders and study the different tunability (by an external static magnetic field) of these PBGs. One type of the band gaps comes from infinitely degenerate flat bands and is closely related to those in the study of plasmonics. In addition, such PBGs are magnetically tunable and robust against position disorder. We calcualte the transmission of the PBG's and found excellent agreement with the results of the photonic band structure calculation. Positional disorder of the lattice structure affects the different types of PBGs differently.Comment: 4 pages, 5 figure

A multi-scale model for studying failure mechanisms of composite wind turbine blades

Composite structures have been widely used in wind turbine equipment for their high stiffness to mass ratio and high strength. A major concern in the use of composite materials is their susceptibility to various micro damage, such as fiber breakage and matrix crack, which will lead to macroscopic structural fracture. In this paper, a multi-scale modeling strategy is proposed to investigate failure mechanisms and damage evolution of composite blades with initial defects from microscopic damage (including fiber fractures and matrix cracks) to macroscopic fracture. At the microscopic scale, an isoparametric micromechanical model is developed to calculate microscopic stresses and simulate microscopic damage. At the laminar scale, the classic laminate theory is employed to evaluate the laminate stiffness. At the structural scale, a reverse modeling technology is proposed to accurately acquire structural dimensions of a wind turbine blade, and a macroscopic 3D model is implemented into ANSYS/LS-DYNA software. By comparing with the experimental data, it is demonstrated that the proposed multi-scale method is suitable to predict mechanical properties of complex composite structures effectively