H. Al-Wahsh

• Professor
• Benha University

New bound in continuum states and long-lived resonances in one photonic triangular pyramid with two semi-infinite leads are reported, together with general theorems giving their existence conditions. The pyramid is composed of connected open loops (of length L). When bound in continuum states exist within state continua, they induce long-lived reso...

We consider, in the frame of long-wavelength Heisenberg model, a simple magnetic device consisting of two dangling side stubs grafted at the same site along a waveguide. This simple structure is designed to obtain bound in continuum (BIC) modes, magnonic induced transparency (MIT) and magnonic induced absorption (MIA), the analogues of electromagne...

We give an analytical demonstration of the possibility to realize a simple magnonic demultiplexer based on induced transparency resonances. The demultiplexer consists on an Y-shaped waveguide with an input line and two output lines. Each line contains two grafted stubs at a given position far from the input line. We derive in closed form the analyt...

This chapter is on phonons in supported slabs. It starts by a presentation of the general equations for an elastic material. General analytic expressions are obtained for bulk and surface Green's functions, as simple examples of the continuous interface response theory of Chapter 1 of this book. With the same coherent approach, many analytical resu...

In this chapter, we discuss the vibrational properties of phononic circuits that can be described in the framework of discrete or continuous models. In the case of discrete media, we use the phonon discrete model within the Green's function method described in Chapter 1 and give the surface response operators necessary to study surface and confined...

In this chapter we study the band gap structures as well as the effect of inhomogeneities within the perfect one-dimensional (1D) phononic crystal (PnC) such as a free surface, a PnC/substrate interface, and a defect layer embedded in these systems. Such inhomogeneities are usually present in actual device structures as a support (substrate) or as...

In this chapter we describe the basic concepts of two-dimensional (2D) phononic crystals. We start with a detailed presentation of the elementary methods for the calculation of band structures and transmission phenomena which have proven their efficiency in the literature. We respectively present the plane wave expansion method, the finite differen...

A general theory of interface response in linear composite systems is presented in the first chapter of this book on phononics. Specific examples, fully developed in the next chapters of this book, are shortly presented in this chapter. Other examples using this general interface response theory appear also in the following books of this interface...

Phononics: Interface Transmission Tutorial Book Series provides an investigation of modern systems that includes a discrete matrix description. Classical continuous systems relying on the use of differential equations are recalled, showing that they generally have a specific limit on their corresponding modern matrix formulation. A detailed descrip...

We present a review of our theoretical calculations about magnon transport in quasi-one-dimensional (1D) magnonic circuits constituted by waveguides coupled to side resonators. Phenomena such as the existence of band gaps, rejective and selective transmissions and Fano resonances will be discussed as well as the applications of these structures in...

In the frame of the long-wavelength Heisenberg model, a simple magnonic mono-mode circuit is designed to obtain transmission stop (pass) bands where the propagation of spin waves is forbidden (allowed). This simple device is composed of an infinite one-dimensional monomode waveguide (the backbone) along which side resonators (symmetric or asymmetri...

. We study, in the frame of the discrete dipole approximation, the magnons propagation through a simple multiplexing device made of chains of magnetic nanoparticles along which a small chains (called a resonators) is attached. We show that this simple structure can transfer with selectivity one magnon frequency from one chain to the other, leaving...

We consider, in the frame of long-wavelength Heisenberg model, the effect of a pinning field on the spin wave band gaps and transmission spectra of a simple magnonic device. This simple device is composed of an infinite one dimensional (1D) monomode waveguide (the backbone) along which N (N’) side resonators are grafted at two sites. Using a Green’...

In the frame of long-wavelength Heisenberg model, a simple magnonic device is designed to obtain possibly transmission stop bands (where the propagation of spin waves is forbidden). This simple device is composed of an infinite one-dimensional mono-mode waveguide (the backbone) along which N(N′) side resonators are grafted at two sites. Contrary to...

A simple acoustic device consisting of two dangling side resonators grafted at two sites on a slender tube is designed possibly to obtain transmission stop bands (where the propagation of longitudinal acoustic waves is forbidden). In contrast to all known systems of this kind, a spectral transmission gap of nonzero width occurs here even with this...

We present a multiplexing device made of nanometric magnetic cluster chains and adsorbed clusters near the chains. We show that this nanosystem can transfer one magnon frequency from one chain to the other. With an appropriate choice of the geometrical or magnetic parameters of the structure, it is possible to control the desired magnon ejection. T...

In the frame of the discrete dipole approximation, the propagation of magnons in quasi-one-dimensional resonant structures made of nanometric magnetic clusters is examined theoretically. These resonant structures, composed of a nanometric magnetic cluster chain and adsorbed clusters near the chain, may exhibit sharp peaks (dips) in the magnon trans...

A simple electronic circuit consisting of a single symmetric or asymmetric loop with dangling resonators is designed to obtain possibly large stop bands (where the propagation of electrons is forbidden). Contrary to all known systems of this kind, a spectral transmission gap of nonzero width occurs here even with a single loop. This is obtained by...

A fundamental understanding of nanoscaled materials has become an important challenge for any technical applications. For magnetic nanoparticles, the investigations are in particular stimulated by the magnetic storage devices. In this paper we present a theory of the magnon propagation in a nanometric chain and of the effects of neighbor magnetic c...

We study theoretically the plasmon mediated propagation of light through a chain of metallic nanoparticles along which a small chain (called a resonator) is attached vertically. The effect of this vertical resonator is to induce peaks and zeros in the transmission power. We show that, with a resonator constituted of two metallic clusters, an approp...

We study the propagation of electromagnetic waves in infinite lines with grafted finite lines in a frequency regime, where the grafted lines have negative phase velocity. The physical properties of such a structure with negative phase velocity materials have not been investigated before, to the best of our knowledge. The theory uses a Green's funct...

Simple nanometric structures enabling the multiplexing and cross-talk transfer of acoustic waves are presented. Such structures are constructed out of two monomode discrete cluster chains and two other clusters situated in between these chains. The clusters interact with one another through the elastic deformation of the substrate on which they are...

A system of equations of motion for the Green functions in layered antiferromagnets such as La2CuO4 and YBa2Cu3O6 has been treated by an “equal access” decoupling scheme. The correlation functions are fully equivalent in this scheme in contrast with the ordinary random-phase approximation (RPA). The method provides a new insight into the nature of...

A multiplexing system which consisted of two discrete plasmon wires coupled by two metal nanoclusters was discussed. It was observed that the directional plasmon ejection was optimized by closed-form relations between the transmission coefficients and the nanocluster distances. An oscillating dipole field was produced by the plasmon excitations, wh...

Simple multiplexing phonon structures are presented. Such structures can be deposited on a surface with current ultra-high vacuum technologies. In the atomic domain they are supposed to be made out of two parallel mono-atomic chains of atoms and of a simple coupling device made out of two other atoms interacting together and with the two chains. We...

We consider, in the frame of the long-wavelength Heisenberg model, the effect of a pinning field on the spin wave band gaps and transmission spectra of one-dimensional comb-like structures. Using a Greens function method, we obtained closed-form expressions for the band structure and the transmission coefficients for an arbitrary value of the numbe...

A magnonic chain of cells consisting of a serial loop structure with dangling resonators (SLS-DRs) is designed to obtain possibly large stop bands. Contrary to all known systems of this kind, a spectral gap of nonzero width occurs here even with a single cell. General expressions for the dispersion relation and for the transmission coefficient are...

The role of interlayer coupling constant on the Néel temperature of layered copper oxides and other magnetic properties have been studied. The theoretical framework is based on anisotropic Heisenberg model and the two sublattice approach. The higher-order Green functions are decoupled using the second random phase approximation. The Green’s functio...

The acoustic band structures and transmissions through a one-dimensional (1D) monomode waveguide made of asymmetric slender tube loops pasted together with slender tubes of finite length are investigated theoretically. These monomode circuits may exhibit large stop bands where the propagation of acoustic waves is forbidden. These stop bands (gaps)...

We present a simple multiplexing device made of two atomic chains coupled by two other transition metal atoms. We show that this simple atomic device can transfer electrons at a given energy from one wire to the other, leaving all other electron states unaffected. Closed-form relations between the transmission coefficients and the inter-atomic dist...

In the frame of the long-wavelength Heisenberg model, the magnonic bandgaps and the selective transmission in a serial loop structure, made of loops pasted together with segments of finite length, are investigated theoretically. The loops and the segments are assumed to be one-dimensional ferromagnetic materials. Using a Green function method, we o...

In the frame of the long-wavelength Heisenberg model, the magnonic band structures and transmission spectra of asymmetric serial loop structures (ASLS), made of asymmetric loops pasted together with segments of finite length, are examined theoretically. These monomode structures, composed of one-dimensional ferromagnetic materials, may exhibit larg...

The magnonic band gaps and the selective transmission in the serial loop structure (SLS), made of loops pasted together with segments of finite length, are investigated theoretically in the frame of the long-wavelength Heisenberg model. These monomode structures, composed of one-dimensional ferromagnetic materials, may exhibit complete gaps. The wi...

In the frame of the long-wavelength Heisenberg model, we investigate the existence of giant gaps in the band structure of a comblike geometry composed of a one-dimensional magnonic waveguide along which N′ dangling side branches are grafted at N equidistant sites. These gaps originate not only from the periodicity of the system but also from the re...

To determine the neutron inelastic coherent scattering (NIS) cross section for disordered magnets a system of equations of motion for the Green functions (GF) related to the localized-spin correlation functions 〈SR+SR′-〉, 〈SR-SR′-〉, and 〈SRzSR′-〉 has been exploited. The higher-order Green functions are decoupled using a symmetric “equal access” (EA...

To determine the neutron inelastic coherent scattering (NIS) cross-section for disordered magnets a system of equations of motion for the Green functions (GF) related to the localized-spin correlation-functions SR+SR′−, SR−SR′−, SRzSR′− has been exploited. The formula for the magnon dispersion relations derived here covers a number of spin structur...

We report the existence of large gaps in the band structure of a comblike structure composed of a one-dimensional magnonic waveguide along which N′ dangling side branches are grafted at N equidistant sites. These gaps originate not only from the periodicity of the system but also from the resonance states of the grafted branches (which play the rol...

A model antiferromagnet consisting of N spins , all interacting among themselves with equal strength, and with the external magnetic field H, was analysed, both for Ising spins and vector spins. Starting from the Hamiltonian, the partition function, specific heat and magnetic susceptibility versus temperature T have been calculated for both systems...