757 research outputs found
Interplane charge dynamics in a valence-bond dynamical mean-field theory of cuprate superconductors
We present calculations of the interplane charge dynamics in the normal state
of cuprate superconductors within the valence-bond dynamical mean-field theory.
We show that by varying the hole doping, the c-axis optical conductivity and
resistivity dramatically change character, going from metallic-like at large
doping to insulating-like at low-doping. We establish a clear connection
between the behavior of the c-axis optical and transport properties and the
destruction of coherent quasiparticles as the pseudogap opens in the antinodal
region of the Brillouin zone at low doping. We show that our results are in
good agreement with spectroscopic and optical experiments.Comment: 5 pages, 3 figure
Asymptotically self-similar propagation of the spherical ionization waves
It is shown that a new type of the self-similar spherical ionization waves
may exist in gases. All spatial scales and the propagation velocity of such
waves increase exponentially in time. Conditions for existence of these waves
are established, their structure is described and approximate analytical
relationships between the principal parameters are obtained. It is notable that
spherical ionization waves can serve as the simplest, but structurally complete
and physically transparent model of streamer in homogeneous electric field.Comment: Corrected typos, the more precise formulas are obtaine
Twisted speckle entities inside wavefront reversal mirrors
The previously unknown property of the optical speckle pattern reported. The
interference of a speckle with an oppositely moving phase-conjugated speckle
wave produces a randomly distributed ensemble of a twisted entities (ropes)
surrounding optical vortex lines. These entities appear in a wide range of
randomly chosen speckle parameters inside the phase-conjugating mirrors
regardless to an internal physical mechanism of the wavefront reversal. These
numerically generated interference patterns are relevant to a Brillouin -mirrors and to a four-wave mixing -mirrors based upon laser trapped
ultracold atomic cloud.Comment: 4 pages,3 figures, Accepted to Physical Review
Extracting the electron--boson spectral function F() from infrared and photoemission data using inverse theory
We present a new method of extracting electron-boson spectral function
F() from infrared and photoemission data. This procedure is
based on inverse theory and will be shown to be superior to previous
techniques. Numerical implementation of the algorithm is presented in detail
and then used to accurately determine the doping and temperature dependence of
the spectral function in several families of high-T superconductors.
Principal limitations of extracting F() from experimental
data will be pointed out. We directly compare the IR and ARPES
F() and discuss the resonance structure in the spectra in
terms of existing theoretical models
Electrodynamics of the Nodal Metal in Weakly Doped High- Cuprates
We report on the detailed analysis of the infrared (IR) conductivity of two
prototypical high- systems YBaCuO and
LaSrCuO throughout the complex phase diagram of these
compounds. Our focus in this work is to thoroughly document the electromagnetic
response of the nodal metal state which is initiated with only few holes doped
in parent antiferromagnetic systems and extends up to the pseudogap boundary in
the phase diagram. The key signature of the nodal metal is the two-component
conductivity: the Drude mode at low energies followed by a resonance in mid-IR.
The Drude component can be attributed to the response of coherent
quasiparticles residing on the Fermi arcs detected in photoemission
experiments. The microscopic origin of the mid-IR band is yet to be understood.
A combination of transport and IR data uncovers fingerprints of the Fermi
liquid behavior in the response of the nodal metal. The comprehensive nature of
the data sets presented in this work allows us to critically re-evaluate common
approaches to the interpretation of the optical data. Specifically we
re-examine the role of magnetic excitations in generating electronic self
energy effects through the analysis of the IR data in high magnetic field.Comment: 14 pages, 11 figure
Stimulated emission of radiation using spin-population inversion in metals: a spin-laser
Arrays of 10 nm-diameter point contacts of exchange-coupled
spin-majority/spin-minority ferromagnetic metals, integrated into
infrared-terahertz range photon resonators, are fabricated and measured
electrically and optically. Giant, threshold-type electronic excitations under
high-current pumping of the devices are observed as abrupt but reversible steps
in device resistance, in many cases in access of 100%, which correlate with
optical emission from the devices. The results are interpreted as due to
stimulated spin-flip electron-photon relaxation in the system.Comment: 5 page
Sum rules and electrodynamics of high-Tc cuprates in the pseudogap state
We explore connections between the electronic density of states (DOS) in a
conducting system and the frequency dependence of the scattering rate
inferred from infrared spectroscopy. We show that changes in
the DOS upon the development of energy gaps can be reliably tracked through the
examination of the spectra using the sum rules discussed in
the text. Applying this analysis to the charge dynamics in high- cuprates
we found radically different trends in the evolution of the DOS in the
pseudogap state and in the superconducting state.Comment: 4 pages, 3 figure
- …