3,098 research outputs found
Microscopic theory of refractive index applied to metamaterials: Effective current response tensor corresponding to standard relation
In this article, we first derive the wavevector- and frequency-dependent,
microscopic current response tensor which corresponds to the "macroscopic"
ansatz and with wavevector- and frequency-independent,
"effective" material constants and
. We then deduce the electromagnetic and optical properties
of this effective material model by employing exact, microscopic response
relations. In particular, we argue that for recovering the standard relation
between the refractive
index and the effective material constants, it is imperative to start from the
microscopic wave equation in terms of the transverse dielectric function,
. On the phenomenological side,
our result is especially relevant for metamaterials research, which draws
directly on the standard relation for the refractive index in terms of
effective material constants. Since for a wide class of materials the current
response tensor can be calculated from first principles and compared to the
model expression derived here, this work also paves the way for a systematic
search for new metamaterials.Comment: minor correction
Linear electromagnetic wave equations in materials
After a short review of microscopic electrodynamics in materials, we
investigate the relation of the microscopic dielectric tensor to the current
response tensor and to the full electromagnetic Green function. Subsequently,
we give a systematic overview of microscopic electromagnetic wave equations in
materials, which can be formulated in terms of the microscopic dielectric
tensor.Comment: consistent with published version in Phot. Nano. Fund. Appl. (2017
Time-Temperature Superposition of Structural Relaxation in a Viscous Metallic Liquid
Bulk metallic glass-forming Pd40Ni10Cu30P20 has been investigated in its equilibrium liquid by quasielastic neutron scattering. The quasielastic signal exhibits a structural relaxation as known from nonmetallic viscous liquids. Even well above the melting point, the structural relaxation is nonexponential and obeys a universal time-temperature superposition. From the mean relaxation times average diffusivities have been determined, resulting in values on a 10^-10 m^2 s^-1 scale, 3 orders of magnitude slower than in simple metallic liquids
General form of the full electromagnetic Green function in materials physics
In this article, we present the general form of the full electromagnetic
Green function which is suitable for the application in bulk materials physics.
In particular, we show how the seven adjustable parameter functions of the free
Green function translate into seven corresponding parameter functions of the
full Green function. Furthermore, for both the fundamental response tensor and
the electromagnetic Green function, we discuss the reduction of the Dyson
equation on the four-dimensional Minkowski space to an equivalent,
three-dimensional Cartesian Dyson equation.Comment: consistent with published version in Chin. J. Phys. (2019
Covariant Response Theory and the Boost Transform of the Dielectric Tensor
After a short critique of the Minkowski formulae for the electromagnetic
constitutive laws in moving media, we argue that in actual fact the problem of
Lorentz-covariant electromagnetic response theory is automatically solved
within the framework of modern microscopic electrodynamics of materials. As an
illustration, we first rederive the well-known relativistic transformation
behavior of the microscopic conductivity tensor. Thereafter, we deduce from
first principles the transformation law of the wavevector- and
frequency-dependent dielectric tensor under Lorentz boost transformations.Comment: consistent with published version in Int. J. Mod. Phys. D (2017
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