arXiv subjects

Pavel V. Prudnikov

Publications and source records attributed to Pavel V. Prudnikov.

7 recordsLinked to original sources

arXiv2026

A Machine-Learning Based Approach to the Evaluation of the Critical Scaling Behavior of Anisotropic Spin Systems

Computational models adequately representing phase transitions and evaluating the critical system parameters are essential for the understanding of the properties of a wide range of materials. Here we propose a machine learning (ML)-based approach to the identification of the critical point in anisotropic spin systems. Our approach implies training of a convolutional neural network (CNN) model from the correlation matrices obtained by Monte Carlo simulations. Next, the pretrained model is employed as a fast estimator of the critical temperature, which can be extracted in several complementary ways from the CNN model inference, this way improving the robustness of the analysis. The ML-based estimates obtained in this study are in very good agreement with the reference Monte Carlo simulation results, while computational costs are about 10x lower compared to the classical thermodynamic approach.

cond-mat.stat-mech↗

arXiv2025

The influence of anisotropy on the manifestation of aging effects in the magnetoresistance of multilayer structures

Currently, aging effects occurring in multilayer systems attract much attention from researchers. In our research we looked at the behavior of multilayer systems that depend on anisotropy, magnetoresistance and susceptibility.All these parameters are interrelated and have varying degrees of influence on the effects of aging. We researched our Co-layers magnetic system from high-temperature and low-temperature initial states, as well as not only in the critical temperature region, but in a wide low-temperature range. The study was carried out with different types of magnetic anisotropy, which made it possible to identify differences in the behavior of the system depending on the type of anisotropy. We found that in systems exhibiting a dimensional transition, aging effects manifest to gain and themselves in a wide low-temperature range, and not only in a narrow near-critical region, which ultimately leads us to a wide range of applications of these materials for practical applications.

cond-mat.mes-hall↗

arXiv2019

Non-equilibrium vortex annealing of structural disorder in Berezinskii-Kosterlitz-Thouless dynamics of two-dimensional XY-model

The non-equilibrium annealing of structural disorder in a two-dimensional XY-model leads to coarsening of defects clusters in a cores of spin vortices. We revealed the effect of "inertial" growth of the clusters in coarsening dynamic regime. The calculated transverse stiffness $ρ(p,T)$ of the system in the high-temperature phase $T>T_{\rm BKT}(p)$ becomes negative and has described by a power low $ρ(p,T) \sim T^{-κ}$ with temperature independent exponent $κ=κ(p)$. The dynamical scaling lead to the dynamic dependence of the correlation length $ξ\sim (t / \ln^{q} (t/t_{0}))^{1/z}$ which can be explained by a shift of spin vortices friction constant $γ$ induced by annealed disorder.

cond-mat.str-el↗

arXiv2015

Dimensional effects in ultrathin magnetic films

Dimensional effects in the critical properties of multilayer Heisenberg films have been numerically studied by Monte Carlo methods. The effect of anisotropy created by the crystal field of a substrate has been taken into account for films with various thicknesses. The calculated critical exponents demonstrate a dimensional transition from two-dimensional to three-dimensional properties of the films with an increase in the number of layers. A spin-orientation transition to a planar phase has been revealed in films with thicknesses corresponding to the crossover region.

cond-mat.stat-mech↗

arXiv2012

Non-equilibrium critical relaxation of the 3D Heisenberg magnets with long-range correlated disorder

Monte Carlo simulations of the short-time dynamic behavior are reported for three-dimensional Heisenberg model with long-range correlated disorder at criticality, in the case corresponding to linear defects. The static and dynamic critical exponents are determined for systems starting from an ordered initial state. The obtained values of the exponents are in a good agreement with results of the field-theoretic description of the critical behavior of this model in the two-loop approximation.

cond-mat.dis-nn↗

arXiv2010

Short-time dynamics and critical behavior of three-dimensional site-diluted Ising model

Monte Carlo simulations of the short-time dynamic behavior are reported for three-dimensional weakly site-diluted Ising model with spin concentrations $p=0.95$ and 0.8 at criticality. In contrast to studies of the critical behavior of the pure systems by the short-time dynamics method, our investigations of site-diluted Ising model have revealed three stages of the dynamic evolution characterizing a crossover phenomenon from the critical behavior typical for the pure systems to behavior determined by the influence of disorder. The static and dynamic critical exponents are determined with the use of the corrections to scaling for systems starting separately from ordered and disordered initial states. The obtained values of the exponents demonstrate a universal behavior of weakly site-diluted Ising model in the critical region. The values of the exponents are compared to results of numerical simulations which have been obtained in various works and, also, with results of the renormalization-group description of this model.

cond-mat.dis-nn↗

arXiv2008

Effect of structural defects on anomalous ultrasound propagation in solids during second-order phase transitions

The effect of structural defects on the critical ultrasound attenuation and ultrasound velocity dispersion in Ising-like three-dimensional systems is studied. A field-theoretical description of the dynamic effects of acoustic-wave propagation in solids during phase transitions is performed with allowance for both fluctuation and relaxation attenuation mechanisms. The temperature and frequency dependences of the scaling functions of the attenuation coefficient and the ultrasound velocity dispersion are calculated in a two-loop approximation for pure and structurally disordered systems, and their asymptotic behavior in hydrodynamic and critical regions is separated. As compared to a pure system, the presence of structural defects in it is shown to cause a stronger increase in the sound attenuation coefficient and the sound velocity dispersion even in the hydrodynamic region as the critical temperature is reached. As compared to pure analogs, structurally disordered systems should exhibit stronger temperature and frequency dependences of the acoustic characteristics in the critical region.

cond-mat.dis-nn↗