arXiv subjects
Publications and source records attributed to Andrei A. Fedorenko.
We study the contribution of stochastic motion of a domain wall (DW) to the dielectric AC susceptibility for low frequencies. Using the concept of waiting time distributions, which is related to the energy landscape of the DW in a disordered medium, we derive the power-law behavior of the complex susceptibility observed recently in some ferroelectrics below Curie temperature.
We study the effect of quenched random field disorder on a driven elastic interface close to the depinning transition at the upper critical dimension d_{c}=4 using the functional renormalization group. We have found that the displacement correlation function behaves with distance x as ln(x)^{2/3} for large x. Slightly above the depinning transition the force-velocity characteristics is described by the equation v ~ f |ln(f)|^{2/9}, while the correlation length behaves as L_{v} ~ f^{-1/2}|ln(f)|^{1/6}, where f=F/F_{c}-1 is the reduced driving force.
We study the energy distribution function $ρ(E)$ for interfaces in a random field environment at zero temperature by summing the leading terms in the perturbation expansion of $ρ(E)$ in powers of the disorder strength, and by taking into account the non perturbational effects of the disorder using the functional renormalization group. We have found that the average and the variance of the energy for one-dimensional interface of length $L$ behave as, $ _{R}\propto L\ln L$, $ΔE_{R}\propto L$, while the distribution function of the energy tends for large $L$ to the Gumbel distribution of the extreme value statistics.
A field-theory approach is used to investigate the ''spin-glass effects'' on the critical behaviour of systems with weak temperature-like quenched disorder. The renormalization group (RG) analysis of the effective Hamiltonian of a model with replica symmetry breaking (RSB) potentials of a general type is carried out in the two-loop approximation. The fixed-point (FP) stability, recently found within the one-step RSB RG treatment, is further explored in terms of replicon eigenvalues. We find that the traditional FPs, which are usually considered to describe the disorder-induced universal critical behaviour, remain stable when the continuous RSB modes are taken into account.
Using the results of the recently studied problem of adsorption of a Gaussian polymer in a weak periodic surface potential we study the influence of a single rod like defect on the polymer being localized in the periodic surface potential. We have found that the polymer will be localized at the defect under condition u>u_c, where u_c is the localization threshold in the periodic potential, for any infinitesimal strength of the interaction with defect. We predict that the concentration of monomers of the localized polymer decays exponentially as a function of the distance to the defect and is modulated with the period of the surface potential.