arXiv subjects

V. A. Osipov

Publications and source records attributed to V. A. Osipov.

43 records · Page 3Linked to original sources

arXiv2005

Low-temperature internal friction and thermal conductivity in plastically deformed metals due to dislocation dipoles and random stresses

The contribution to the low frequency internal friction and the thermal conductivity due to optically vibrating edge dislocation dipoles is calculated within the modified Granato-Lucke string model. The results are compared with the recent experiments on plastically deformed samples of Al, Ta and Nb at low temperatures. It is shown that the presence of a reasonable density of optically vibrating dislocation dipoles provides a good fit to the thermal conductivity in superconducting samples. At the same time, the internal friction experiments can not be described within the standard fluttering string mechanism. We found that the problem can be solved by assuming random forces acting on the dislocation dipoles. This gives an additional contribution to the internal friction which describes well the experimental data at low temperatures while their contribution to the thermal conductivity is found to be negligible.

cond-mat.dis-nn↗

arXiv2002

p-Adic description of characteristic relaxation in complex systems

This work is a further development of an approach to the description of relaxation processes in complex systems on the basis of the p-adic analysis. We show that three types of relaxation fitted into the Kohlrausch-Williams-Watts law, the power decay law, or the logarithmic decay law, are similar random processes. Inherently, these processes are ultrametric and are described by the p-adic master equation. The physical meaning of this equation is explained in terms of a random walk constrained by a hierarchical energy landscape. We also discuss relations between the relaxation kinetics and the energy landscapes.

cond-mat.dis-nn↗

arXiv2000

Disclination vortices in elastic media

The vortex-like solutions are studied in the framework of the gauge model of disclinations in elastic continuum. A complete set of model equations with disclination driven dislocations taken into account is considered. Within the linear approximation an exact solution for a low-angle wedge disclination is found to be independent from the coupling constants of the theory. As a result, no additional dimensional characteristics (like the core radius of the defect) are involved. The situation changes drastically for 2πvortices where two characteristic lengths, l_ϕand l_W, become of importance. The asymptotical behaviour of the solutions for both singular and nonsingular 2πvortices is studied. Forces between pairs of vortices are calculated.

patt-sol↗

arXiv1999

Gauge theory of disclinations on fluctuating elastic surfaces

A variant of a gauge theory is formulated to describe disclinations on Riemannian surfaces that may change both the Gaussian (intrinsic) and mean (extrinsic) curvatures, which implies that both internal strains and a location of the surface in R^3 may vary. Besides, originally distributed disclinations are taken into account. For the flat surface, an extended variant of the Edelen-Kadic gauge theory is obtained. Within the linear scheme our model recovers the von Karman equations for membranes, with a disclination-induced source being generated by gauge fields. For a single disclination on an arbitrary elastic surface a covariant generalization of the von Karman equations is derived.

math-ph↗

arXiv1999

Transport in Materials with Disclination Dipoles: Applications to Polycrystals and Amorphous Dielectrics

The problem of both electron and phonon scattering by wedge disclination dipoles (WDD) is studied in the framework of the deformation potential approach. The exact analytical results for the mean free path are obtained within the Born approximation. The WDD-induced contribution to the residual resistivity in nanocrystalline metals is estimated. Using the WDD-based model of a grain boundary, the thermal conductivity, kappa, of polycrystals and amorphous dielectrics is studied. It is shown that the low-temperature crossover of kappa experimentally observed in LiF, NaCl, and sapphire can be explained by the grain-boundary phonon scattering. A combination of two scattering processes, the phonon scattering due to biaxial WDD and the Rayleigh-type scattering, is suggested to be of importance in amorphous dielectrics. Our results are in a good agreement with the experimentally observed kappa in a-SiO_2, a-GeO_2 a-Se, and polystyrene over a wide temperature range.

cond-mat.mtrl-sci↗

arXiv1998

Disclination Dipoles as the Basic Structural Elements of Dielectric Glasses

We show that the experimentally observed behavior of thermal conductivity of dielectric glasses over a wide temperature range can be explained by a combination of two scattering processes. The first one comes from the phonon scattering due to biaxial dipoles of wedge disclinations while the second one is the Rayleigh type scattering. The results obtained support the cluster picture suggested earlier for glassy materials.

cond-mat.mtrl-sci↗

arXiv1998

Towards the grain boundary phonon scattering problem: an evidence for a low-temperature crossover

The problem of phonon scattering by grain boundaries is studied within the wedge disclination dipole (WDD) model. It is shown that a specific q-dependence of the phonon mean free path for biaxial WDD results in a low-temperature crossover of the thermal conductivity, $κ$. The obtained results allow to explain the experimentally observed deviation of $κ$ from a $T^3$ dependence below $0.1K$ in $LiF$ and $NaCl$.

cond-mat.mtrl-sci↗