Local-field effects and effective-medium theory: A microscopic perspective

Abstract

Standard textbook derivations of the Clausius–Mossotti (Lorentz–Lorenz) relation tend to obscure the physical origin of local-field effects by proceeding from the macroscopic dielectric function of the equivalent homogeneous system to the microscopic parameters of the model. The microscopic and macroscopic aspects can be made clearer by reversing the order, that is, by first obtaining the microscopic solution and then implementing the definition of macroscopic quantities as averages of their microscopic counterparts. This approach also leads naturally into a treatment of effective-medium theory and the description of the dielectric response of heterogeneous materials.

Impedance model for the polarization-dependent optical absorption of superconducting single-photon detectors

“…Since only the imaginary part of eff determines the absorption in the film, the absorption of the detector can simply be calculated by multiplying the thickness of the film by the filling factor. For the polarization perpendicular to the wires of the detector, it is not so straightforward to define an effective dielectric constant for the patterned film [14,15]. For this polarization the light is concentrated in the air slits and the effective dielectric constant is closer to that of air.…”

“…For the typical dimensions and spacing of the NbN wires, an effective medium approach that is accurate for both polarizations is difficult [14,15]. Instead, we calculated the absorption at normal incidence for an infinitelysized detector, using the rigorous coupled-wave analysis (RCWA) developed in reference [16].…”

“…The thickness for which the absorption in the patterned film is maximum, is higher than the optimal thickness for the closed film. The dotted line is calculated using the impedance model of Section 4, taking an effective dielectric constant for the absorbing film, given by [14] …”

Metal nanoparticles in a photovoltaic cell: Effect of metallic loss

“…2. It is clear that the continuity of electric displacement prevails: 22 the majority of electric flux lines end up with the metal, i.e., the local field (the field between the nanoparticles) originates from the strong near field of the MNPs. Combining the absorption expression (Eq.…”

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

“…This chapter introduces the fundamental physics and concepts of dielectrics [30][31][32][33][34][35][36][37][38][39] and their classification [38][39][40][41][42][43][44][45][46] , as well as of ferroelectrics 2,16,29,[37][38][39][40][41][42][43][44][45][46][47][48][49][50] , and relaxor ferroelectrics. [51][52][53][54][55][56][57] The information of many textbooks and review papers related to the physics of materials science was employed throughout these sections.…”