1,666 research outputs found
Universal dielectric loss in amorphous solids from simultaneous bias and microwave field
We derive the ac dielectric loss in glasses due to resonant processes created
by two-level systems and a swept electric field bias. It is shown that at
sufficiently large ac fields and bias sweep rates the nonequilibrium loss
tangent created by the two fields approaches a universal maximum determined by
the bare linear dielectric permittivity. In addition this nonequilibrium loss
tangent is derived for a range of bias sweep rates and ac amplitudes and show
that the loss tangent creates a predicted loss function that can be understood
in a Landau-Zener theory and which can be used to extract the TLS density,
dipole moment, and relaxation rate.Comment: To appear in Physical Review Letters, 4 pages, 3 figure
Optical modes in linear arrays of dielectric spherical particles: A numerical investigation
We have investigated bound modes in finite linear chains of dielectric
particles of various lengths, interparticle spacing and particle materials.
Through a unique application of the multisphere Mie scattering formalism, we
have developed numerical methods to calculate eigen-optical modes for various
arrays of particles. These numerical methods involve the use of the multisphere
scattering formalism as the entries in NxN matrices where N represents the
number of particles in the chain. Eigenmodes of these matrices correspond to
the eigen-optical modes of interest. We identified the eigenmodes with the
highest quality factor by the application of a modified version of the
Newton-Raphson algorithm. We found that convergence is strong using this
algorithm for linear chains of up to several hundreds of particles. By
comparing the dipolar approach with the more complex approach which utilizes a
combination of both dipolar and quadrupolar approaches, we demonstrated that
the dipolar approach has an accuracy of approximately 99%. We found that the
quality factor Q of the mode increases with the cubed value of the number of
particles in chain in agreement with the previously developed theory, the
effects of disordering of particle sizes and inter-particle distances will be
discussed.Comment: Submitted to Proceedings of SPI
Memory effects in transport through a hopping insulator: Understanding two-dip experiments
We discuss memory effects in the conductance of hopping insulators due to
slow rearrangements of many-electron clusters leading to formation of polarons
close to the electron hopping sites. An abrupt change in the gate voltage and
corresponding shift of the chemical potential change populations of the hopping
sites, which then slowly relax due to rearrangements of the clusters. As a
result, the density of hopping states becomes time dependent on a scale
relevant to rearrangement of the structural defects leading to the excess time
dependent conductivity
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