arXiv subjects

Valerii M. Vinokur

Publications and source records attributed to Valerii M. Vinokur.

41 records · Page 3Linked to original sources

arXiv1997

Hysteretic Depinning of Anisotropic CDW

We investigate the depinning transition in a dirty periodic medium considering a model of layered charge density waves as a prototype system. We find that depinning from strong disorder occurs via a two stage process, where, first, the pinned system experiences a continuous transition into a plastically sliding state and undergoes a second sharp hysteretic transition into a coherently moving 3D state at higher drives. In the weakly disordered system the depinning into a coherently sliding state remains continuous.

cond-mat.dis-nn↗

arXiv1996

Glassy Motion of Elastic Manifolds

We discuss the low-temperature dynamics of an elastic manifold driven through a random medium. For driving forces well below the $T=0$ depinning force, the medium advances via thermally activated hops over the energy barriers separating favorable metastable states. We show that the distribution of waiting times for these hopping processes scales as a power-law. This power-law distribution naturally yields a nonlinear glassy response for the driven medium, $v\sim\exp(-{\rm const}\times F^{-μ})$.

cond-mat↗

arXiv1995

Columnar defects and vortex fluctuations in layered superconductors

We investigate fluctuations of Josephson-coupled pancake vortices in layered superconductors in the presence of columnar defects. We study the thermodynamics of a single pancake stack pinned by columnar defects and obtain the temperature dependence of localization length, pinning energy and critical current. We study the creep regime and compute the crossover current between line-like creep and pancake-like creep motion. We find that columnar defects effectively increase interlayer Josephson coupling by suppressing thermal fluctuations of pancakes. This leads to an upward shift in the decoupling line most pronounced around the matching field.

cond-mat↗

arXiv1995

Creep in One Dimension and Phenomenological Theory of Glass Dynamics

The dynamics of a glass transition is discussed in terms of the motion of a particle in a one dimensional correlated random potential. An exact calculation of the velocity $V$ under an applied force $f$ demonstrates a variety of dynamic regimes depending on the range of correlations. In a gaussian potential with correlator $C(x) = x^γ$, we find a transition from ohmic behaviour ($γ<0$) to creep motion $V \sim \exp(- const/f^μ )$ ($0<γ<1$). This provides a generic picture of the glass transition in systems where long range correlations in the effective disorder develop due to elasticity such as elastic manifolds subject to quenched disorder and the vortex glass transition in superconductors.

cond-mat↗

arXiv1993

Low-Temperatures Vortex Dynamics in Twinned Superconductors

We discuss the low-temperature dynamics of magnetic flux lines in samples with a family of parallel twin planes. A current applied along the twin planes drives flux motion in the direction transverse to the planes and acts like an electric field applied to {\it one-dimensional} carriers in disordered semiconductors. As in flux arrays with columnar pins, there is a regime where the dynamics is dominated by superkink excitations that correspond to Mott variable range hopping (VRH) of carriers. In one dimension, however, rare events, such as large regions void of twin planes, can impede VRH and dominate transport in samples that are sufficiently long in the direction of flux motion. In short samples rare regions can be responsible for mesoscopic effects.

cond-mat↗