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Mladen Georgiev

Publications and source records attributed to Mladen Georgiev.

At least 19 recordsLinked to original sources
arXiv2011

Bond polarons and high-Tc superconductivity in single layer La_(2-x)Sr_xCuO_4: normal state currents and pairing

We use the term "bond polaron" for a phonon coupled entity which makes the link between neighboring conductive CuO_2 layers in high-Tc superconductive materials. The link is essential for the superconductivity which requires a long range phase coherence in addition to pairing of carriers. The linkage features studied point to a process which is less dependent on the doped hole density implanted as x in the solid solution. The analysis applies to single layered materials mostly but may help understand multilayer ones as well.

physics.gen-ph↗
arXiv2011

The London model of Van-der-Waals forces: what's next?

London's polarization model is extended over a wide range of VdW attraction. At low temperature the VdW attraction is the main competitor to the Casimir force. As the temperature is raised, the VdW force decreases by virtue of the polsrizability falling down gradually. This trend is advanced in multilevel systems. such as the off-center defects, where the polarizability is renormalized through electron-vibrational mode coupling to gain a multiple vibronic enhancement by many orders of magnitude. Applications to high-Tc superconductivity and cosmology are conceivable.

physics.gen-ph↗
arXiv2010

Small polaron confinement revisited

Confinement processes arranging small polarons into insulating periodic structures above certain conversion tempereture are considered. Vibronic (Jahn-Teller) polarons associating inherent electric & magnetic dipoles coupled to external fields lead to colossal field effects. Confinement modes based on Poisson-Boltzmann equations of electrostatic strings and plates are deduced.

physics.chem-ph↗
arXiv2010

Speculations on events in the very early universe beyond the standard model: 0th generation stage immediately following the big bang

We suggest that by virtue of the very early processes immediately following the big bang incipient 1st generation particles are created forming periodic strings to confine the quarks. These strings may be described either by the Laplace equation, due to vanishing space charges, or by Poisson-Boltzmann (PB) equation, due to finite charges. We also propose that the supersymmetry created by the big bang is broken through extended vibronic mixing at the end of the 0th generation giving rise to the diversity of atoms and molecules at the later stages of the evolving universe. We choose quark confinement by electrostatic strings supplied by 2D solutions of the PB equation.

physics.gen-ph↗
arXiv2009

Statistical transfer rates associated with higher-symmetry potential-energy wells in solids: Application to photoinduced desorption and electrification

A current series of papers on barrier-controlled and trapping processes in solids and/or at solid surfaces have laid down the emphasis onto describing the statistical event by means of the barrier currents method due to Bardeen and Christov. The present study centered on photodesorption and photoelectrification is the fourth of an arXiv series which also included rapid statistical approaches to nucleation, diffusion and drift currents in state of the art materials. We presently extend our arguments to spherical square and oscillatory wells to deal with the photoprocesses.

cond-mat.mtrl-sci↗
arXiv2009

Migration of photogenerated charge carriers in silver halides: small polaron transport

Nearly half a century ago, I joined an ambitious research project aimed at establishing the mechanism of photodecomposition of ionic salts. We measured the mobilities and lifetimes of photoelectrons and photoholes in silver bromide in order to get an early-stage knowledge of the process. The last pairs of quantities to study were the diffusion coefficients for which we got results, highly controversial at that time. Now we show that the diffusion data suggest the formation of itinerant Jahn Teller small polarons as the next-stage photo-carriers in silver halides.

cond-mat.mtrl-sci↗
arXiv2009

Mode-coupled barrier-controlled atomic processes in solids: a comparative study

Four basic processes are envisioned, among them migration (diffusion), local rotation (reorientation), isothermic chemical reactions and nucleation. All of them are unified by a common approach to the barrier currents that has been suggested as far back as 1961 by John Bardeen and then extended by Stefan Christov some ten years later. By introducing the respective radial potentials, we incorporate Schroedinger's equation and thereby a quantum insight into the phenomena. Numerical calculations of the obtained statistical transition rates are reported.

cond-mat.mtrl-sci↗
arXiv2009

Transient and quantal nucleation in solids: a statistical approach

In a recent arXiv preprint we proposed a statistical approach to the quantal effects in nucleation rate, addressed particularly to solid state physics. We now turn to transient nucleation rates incorporating either classical or quantal statistics. A similar method may be applied to tackle nucleation problems in anyon systems in 2D solids.

cond-mat.mtrl-sci↗
arXiv2009

Theory of a quantum-mechanical nucleation rate: classical vs. quantal nucleation

We address problems arising in supersaturated systems of small atomic particles in solids. Nucleation processes in such systems do not seem to follow the classical interpretation but may be indicative of quantal nucleation partucularly at higher supersaturations. We reconcile Gibbs' free energy DeltaG vs. particle radius r dependence with the double-well oscillator energy vs. configurational coordinate q dependence to take advantage of the solution of a well-known eigenvalue problem. Theoretical results are presented and compared with experimental data.

cond-mat.mtrl-sci↗
arXiv2009

3-D off-center Li+ rotors in alkali halides: solving for the eigenvalue problem

We are dealing with the long-standing problem of the eigenstates and eigenvalues of 3-D rotators by off-center impurity ions in alkali halides. The ion runs along the brim of a sombrero-like vibronic potential. The quantum-mechanical motion depending on two angular coordinates, we consider the motion along theta at averaged phi, and vice versa. We find the off-center ion performing two rotations: one in (x,y) plane along the azimuth phi and another one along the position angle theta, respectively, which are both described as Mathieu's non-linear oscillators. The motion along z is complemented by an anharmonic vibrational mode.

cond-mat.mtrl-sci↗
arXiv2008

Off-center defects in crystals revisited: dynamic features

A survey is presented of the dynamic features of non-itinerant off-center defects in crystals, such as rotation-like reorientation of isolated species by either impurity or host ions. The occurrence of off-center displacements in electron-vibrational mode systems is regarded as due to the vibronic effects. It is extendable to systems in other fields of physics, e.g. nuclear matter. The latter extension is found to be effective through re-scaling of energies and separations.

physics.chem-ph↗
arXiv2008

Parity non-conservation in beta-decay of nuclei: revisiting experiment and theory fifty years after. IV. Parity breaking models

This part offers a survey of models proposed to cope with the symmetry-breaking challenge. Among them are the two-component neutrinos, the neutrino twins, the universal Fermi interaction, etc. Moreover, the broken discrete symmetries in physics are very much on the agenda and may occupy considerable time for LHC experiments next year aimed at revealing the symmetry-breaking mechanisms.

physics.hist-ph↗
arXiv2008

Survey of vibronic polarons (precursors or full blown) and their role in the universe: an enigma to be possibly solved by LHC

Vibronic polarons (charge carriers coupled to their produced Jahn-Teller distortions) have been extended for some time in relevance to the buildup of matter and the breakdown of supersymmetry at the early stages of the universe, as well as to a number of well established though not fully understood phenomena of everyday life, such as helical propagation, colossal magneto-resistance, etc. We review some of the advances and suggest new ones. Many of them can be verified by Large Hadron Collider (LHC) experiments.

cond-mat.other↗
arXiv2008

Vibronic potentials in chemical physics: adiabatic approximation vs. supersymmetry

We analyze the supersymmetric features of isolated double-well potentials, both symmetric ones and ones under an asymmetric perturbation. Our studies are in concert with results obtained elsewhere. Further on, a particular interest is paid to double- and single-valley potentials occurring in pairs on applying the adiabatic approximation to coupled electron-vibrational mode systems. Among the latter are Holstein's small polarons and the vibronic (off-center) band-species performing a finite-orbital-momentum helical motion. Our results seem to revive an earlier assertion for the existence of artifacts in the adiabatic approximation.

physics.chem-ph↗
arXiv2008

Extended Jahn-Teller effects in fermion-boson systems revisited

Following earlier suggestions, we now redefine our proposal for extending the Jahn-Teller coupling beyond the framework of the electron-phonon interactions so as to cover fermion-boson interactions on a broader energy scale. Our basic unit is an extended "vibronic polaron" (VP), a fermion, itinerant or localized, along with the associated distortion of its boson cloud. A fingerprint of the itinerant unit is the helical form of VP propagation, else the occurrence of an orbital angular momentum for the free carrier. Examples for extended VP's are provided by LG-mode laser beams and, possibly, neutrino-meson coupled units. Our VP theory relates to supersymmetry where it accounts for symmetry breaking, both external and internal ones.

hep-th↗
arXiv2008

Photoinduced electrification of solids. IV. Space charge effects assessed

Our recent arXiv preprints have described the experimental evidence for the universal occurrence of short circuit photocurrents on illumination of solid state surfaces by strongly absorbed light. A likely mechanism has been proposed based on the photodesorption of surface ions to the surrounding atmosphere. Analyses have been made of observed oscilloscope tracings of short circuit photo voltages in terms of the linear rate theory in fair concomitance. Space charge effects having been left unaccounted for, we now propose an approach to them in the diffusion-free approximation.

cond-mat.mtrl-sci↗