Surface acoustic waves at a free-metallized interface

Light scattering was used to study surface acoustic waves at a free-metalized interface on piezoelectric lithium niobate. An interaction region of several acoustic wavelengths was observed in which a reflected surface wave and a continuous spectrum of bulk waves are generated.     

Surface waves at the boundary of a chiral medium

The exact analytical solution of the dispersion relation for the propagation constant of the surface waves existing at the plane interface between chiral and magnetodielectric media is given and studied. An enhancement of the chirality effect due to matching of the permittivities of the media is noted.     

Is physics at the threshold of a new stage of evolution?

Starting from Planck's thesis concerning the aims and methods of theoretical physics as stated in his famous lecture (Leiden, 1908) onDie Einheit des physikalischen Weltbildes and his lectures in the next year at Columbia University, we discuss some aspects of physics and mathematics in our time. We compare relativity theory, quantum mechanics, and atomic physics at their inception with the situation today in field theories, elementary particle physics, and mathematical physics.     

Surface state scattering at a buried interface

The free-electron-like surface state of Mg(0001) is strongly modified in thin films grown on W(110). The long bulk penetration length of its wave function makes it sensitive to the reflective properties of the buried interface, and hence to the complex electronic structure of the substrate. In particular we find a many-fold splitting of the Mg surface band by entering a wide projected band gap of W(110). There is a strong thickness-dependent two-band splitting, which is a clear signature of the formation of a surface-interface resonant state. An additional split-off from these two surface bands is explained by the substrate induced spin-orbit interaction.     

Surface electromagnetic waves at a superconductor-dielectric interface

This paper reports on the results of investigating the frequency dependence, the structure, and the polarization-and energy-related characteristics of surface electromagnetic waves propagating along a superconductor-dielectric interface. An expression for the complex permittivity of a superconductor is derived in the approximation of a two-component plasma containing “normal” and “superconducting” electrons. Basic relations are obtained in the general case at temperatures T≤T _c (where T _c is the critical temperature) and in the limiting case at T?T _c, when the contribution from normal electrons to the permittivity of the superconductor can be disregarded.     

左手系材料界面上的非线性TE电磁波

针对电磁波在非线性左手系材料中的传播性质, 分别研究了左、右手系材料界面以及两左手系材料界面上非线性TE表面波的传播行为讨论了导波的频率特性、色散关系以及群速度随频率的变化规律分析表明,两种界面上的非线性TE表面波均存在频率通带和禁带,且带宽是传播功率的函数揭示了在一定条件下,左、右手系材料界面上既可以支持正向传播的非线性TE表面波,也可以支持反向传播的非线性TE表面波;两左手系材料界面上表面波的传播性质因材料参量的变化差异较大,一定参量条件下,该界面上仅支持反向传播的非线性TE表面波.     

Surface states at the metal-electrolyte interface

A survey is given of the study of surface states at metal-electrolyte interfaces, which comprises both crystal-induced and image-potential-induced states. Because the energetic position varies with electrode potential, surface states can be conveniently investigated in an electrochemical cell by electroreflectance spectroscopy. It is demonstrated that crystal-induced surface states can act as a probe for the potential gradient inside the electric double layer and hence can yield valuable information on interfacial properties. Furthermore, the influence of anion adsorption on surface states, the appearance of surface states in thin metal overlayers with increasing film thickness and the monitoring of surface reconstruction by surface states are briefly discussed.     

Karl Popper at ninety: Highlights of a lifelong intellectual quest

On the occasion of his ninetieth birthday, Karl Popper's lifelong pursuit of answers in several areas of scientific and philosophical thinking is briefly traced, mainly with reference to excerpts from his own writings.     

Magnetic Excitation at the Surface of a Substitutionally Disordered Antiferrornagnet

The magnetic excitation at the auiface of a substitutionally disordered antiferromagnet is etudied by using the Bethe-lattice method. Some numerical resulte are presented.     

Surface spin waves in ferromagnetic thin films

Surface spin-wave modes are calculated for (100) surface of simple cubic structure. An isotropic part as well as an anisotropic part are introduced in the spin Hamiltonian. The anisotropic factor is allowed to vary on the first two surface layers. Dispersion curves are derived by a Green function formalism.The authors are indebted to Dr A. P. Legrand for his help in numerical calculations and to Dr J. Korringa for his continuous encouragement and suggestions.     

Surface states at the metal-electrolyte interface

Normal incidence electroreflectance spectra of Ag and Au single crystal electrodes in aqueous electrolytes reveal pronounced structural features, which can be assigned to optical transitions involving empty surface states. The transition energies show a marked dependence on the electrode potential as predicted by the calculation of Ho, Harmon and Liu. It is demonstrated that electroreflectance of metal electrodes in the double layer charging region is a sensitive tool for studying metallic surface states.     

Memories of the Early Days at SRF

I joined Geoff Marr's UV spectroscopy group at Reading University as a postdoc in the autumn of 1970, to work on his SR programme either at the 330 MeV synchrotron at Glasgow University or on the new project at the Daresbury 5 GeV synchrotron. I chose the latter as it seemed much more exciting and was entirely new, although I did play a minor part in his work at the Glasgow machine, together with an Australian postdoc Mervyn Lynch. This machine used to run at 4 Hz at a current around a tenth of a milliamp, but even so, the Reading group carried out the first experiments on photoelectron angular distributions and partial cross-sections on the rare gases. The data were not conclusive but showed what could be done if more intensity were available.     

Surface optical waves at the boundary with a nonlinear Kerr medium

A rigorous solution consistent with a plane wave approximation is given to the boundary problem for Maxwell’s equations for surface optical waves at the boundary with a nonlinear Kerr medium. Exact formulas for the flux intensity (J ₀) and energy density (W ₀) of these waves are derived depending on the parameters of the adjacent media and the propagation constant (ξ). It is shown that these variables as functions of ξ have minima. Thus, J ₀ and W ₀ increase sharply as the propagation constant deviates from the minimum value ξ_min. Their values are greater, the larger the difference between the dielectric constants of the linear and nonlinear media is. An expression for the propagation velocity of a nonlinear surface wave is also obtained.     

Surface polariton reflection and transmission at a rough surface

A study of surface polariton electric fields incident on a periodic rough surface is done. Expression for the components of the diffuse reflected and transmitted fields are calculated to first order in the roughness amplitude. The frequency dependence of the reflection and transmission factors is found to have a structure within the surface polariton frequency range. Results are illustrated by a rough surface GaP-vacuum system.     

Surface Plasmon Polaritons at the Boundary of a Graphene-Based Thin-Layer Medium

Physics of the Solid State - Properties of surface plasmon polaritons of the TM type at the interface of an isotropic insulator and a periodic graphene–insulator structure have been...     

Surface polaritons at the interface between a polarized Dirac vacuum and a normal metal

The behavior of surface polaritons that can propagate along a flat interface between a polarized Dirac vacuum and a normal metal is studied. Dispersion relations for the surface wave are derived for different field polarizations, and the frequency domains where this wave may exist are found. It is shown that a constant electric field polarizing a Dirac vacuum can be determined from experiments on surface wave excitation.     

Surface Plasma Waves at a Rough Interface of a Solid

The dispersion law for surface polaritons in an inhomogeneous plasma is obtained and studied. The plasma is formed by surface electron states at the interface of a solid under conditions where the irregularity scale is much greater than the wavelength. It is shown that the irregularity of the plasma results in spatial dispersion of surface electrostatic oscillations.     

Surface waves at the interface between a dielectric and a topological insulator

Surface waves that propagate along the interface between an isotropic linear or nonlinear (of the Kerr type) dielectric and a topological insulator have been studied theoretically. A dispersion relation for surface waves, which are represented by superpositions of TE and TM waves, has been obtained. This hybridization occurs because, upon passage through the interface, the polarization of a surface wave changes, which is caused by an induced surface current (which is transverse to the electric field vector of the wave). The surface current of this kind is characteristic of topological insulators. Expressions for the energy flux transferred by a surface wave have been given.     

Surface waves at the interface between a metal and a photovoltaic-photorefractive crystal

We investigate surface waves at the interface between a metal and a photovoltaic-photorefractive (PP) crystal. These surface waves appear in several forms: delocalized surface waves, shock surface waves, and localized surface waves. Only localized surface waves have limited energy. We demonstrate that the transverse sizes of localized surface waves decrease with an increase in the propagation constant and the amplitudes of localized surface waves increase with the propagation constant. The stability of localized surface waves is investigated numerically and it is found that they are stable.     

Surface ordering transitions at a liquid crystal-solid interface above the isotropic smectic-A transition

The degree of orientational order induced by confining cylindrical surfaces is monitored via deuteron nuclear magnetic resonance linesplitting and linewidth above the smectic-A to isotropic phase transition. The orientational order strongly depends on the length of the surfactant coupling molecule, on the surface coverage, and on the liquid crystal. Continuous and stepwise growth of orientational order and surface-induced orientational order transitions found in the isotropic phase are explained in terms of a simplified model of surface-induced layering and molecular self-diffusion.