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## Равновесная форма поверхности кристаллов 4He вблизи критических ориентаций

Успехи физических наук. 2018. Т. 188. № 11. С. 1199-1202.

Андреев А. Ф., Л.А.Мельниковский

Conditions for applicability of mean field theory to the thermodynamics of the 4He crystal surface are determined. Although the faceting transition itself is of Berezinsky—Kosterlitz—Thouless type, the thermodynamic potential outside a narrow neighborhood of the transition temperature can be expanded in the spirit of the Landau theory of second-order phase transitions. The Ginzburg—Levanyuk parameter is estimated. The singular behavior of the surface stiffness near critical directions observed for essentially non-critical temperatures is explained.

Andreev A. F., Melnikovsky L.A., Journal of Experimental and Theoretical Physics 2017 Vol. 124 No. 6 P. 920-923

The conditions for applicability of the mean field theory for describing the thermodynamics of the surface of 4He crystals are investigated based on analysis of experimental data. It is found that although the faceting phase transition itself is a Berezinsky–Kosterlitz–Thouless phase transition, the thermodynamic potential outside a narrow neighborhood of the transition temperature can be ...

Added: February 23, 2018

O.I. Utesov, Syromyatnikov A. V., Journal of Magnetism and Magnetic Materials 2021 Vol. 527 Article 167732

We discuss theoretically a frustrated Heisenberg antiferromagnet in magnetic field close to the saturation one. It is demonstrated that a small biaxial anisotropy and/or the magnetic dipolar interaction produce a delicate balance between phases with a commensurate canted, incommensurate helical (conical), and fan spin orderings. As a result, different sequences of phase transitions are realized ...

Added: February 4, 2021

Shchur L., / Cornell University. Series arXiv "math". 2021. No. 2107.02406.

In the late 80s and 90s, theoretical physicists of
the Landau Institute for Theoretical Physics designed and
developed several specialized computers for challenging
computational problems in the physics of phase transitions.
These computers did not have a central processing unit. They
optimize algorithms to handle elementary operations on
integers - read, write, compare, and count. The approach
allowed them to achieve recording ...

Added: July 26, 2021

Седых В. Д., Rybchenko O., Барковский Н. В. et al., Поверхность. Рентгеновские, синхротронные и нейтронные исследования 2021 № 11 С. 28-33

The structural features and valence states of Fe in substituted strontium ferrite Sr2LaFe3O9–δ after
a series of annealing events in vacuum at different temperatures from 400°C to 650°C are studied by X-ray
diffraction (XRD) and Mssbauer spectroscopy. According to X-ray data, the two samples with extreme (in
terms of oxygen content) compositions (Sr2LaFe3О9 and Sr2LaFe3О8) are single phase ...

Added: October 26, 2022

Utesov O., Physical Review B: Condensed Matter and Materials Physics 2022 Vol. 105 Article 054435

A simple mean-field description of frustrated antiferromagnets on hexagonal lattices, aimed to describe the
high-temperature part of the temperature-magnetic field phase diagram, is proposed. It is shown that an interplay
between modulation vector symmetry, Zeeman energy, and magnetodipolar interaction leads to stabilization of
the triple-Q skyrmion lattice in a certain region of the phase diagram. The corresponding analytical ...

Added: March 2, 2022

O.I. Utesov, Syromyatnikov A. V., Physical Review B: Condensed Matter and Materials Physics 2019 Vol. 100 No. 5 P. 054439

We discuss theoretically phase transitions in frustrated antiferromagnets with biaxial anisotropy or dipolar
forces in magnetic field applied along the easy axis at T = 0. There are well-known sequences of phase
transitions on the field increasing: the conventional spin-flop transition and the flop of the spiral plane at strong
and weak easy-axis anisotropy, respectively. We argue that ...

Added: January 16, 2021

O.I. Utesov, Syromyatnikov A. V., Journal of Magnetism and Magnetic Materials 2019 Vol. 475 P. 98-102

We provide a theoretical description of frustrated multiferroic MnI2 with a spiral magnetic ordering in magnetic field h. We demonstrate that subtle interplay of exchange coupling, dipolar forces, hexagonal anisotropy, and the Zeeman energy account for the main experimental findings observed recently in this material (Kurumaji et al., Phys. Rev. Lett. 106 (2011) 167206). We ...

Added: January 16, 2021

Sergeev T. T., Zyablovsky A. A., Andrianov E. S. et al., Scientific Reports 2021 Vol. 11 Article 24054

We demonstrate a new type of non-Hermitian phase transition in open systems far from thermal equilibrium, which can have place in the absence of an exceptional point. This transition takes place in coupled systems interacting with reservoirs at different temperatures. We show that the spectrum of energy flow through the system caused by the temperature ...

Added: January 2, 2022

Barash L., Marshall J., Weigel M. et al., / Cornell University. Series cond-mat "arxiv.org". 2018. No. 1808.04340.

Estimating the density of states of systems with rugged free energy landscapes is a notoriously difficult task of the utmost importance in many areas of physics ranging from spin glasses to biopolymers to quantum computing. Some of the standard approaches suffer from a spurious convergence of the estimates to metastable minima, and these cases are ...

Added: October 17, 2018

Budkov Y., Kalikin N., Kolesnikov A. L., Chemical Communications 2021 Vol. 57 P. 3983-3986

We develop a new quantitative molecular theory of liquid-phase dipolar polymer gels. We model monomer units of the polymer network as a couple of charged sites separated by a fluctuating distance. For the first time, within the random phase approximation, we have obtained an analytical expression for the electrostatic free energy of the dipolar gel. ...

Added: March 26, 2021

Astrakharchik G., Kryuchkov P., Kurbakov I. et al., Crystals 2018 Vol. 8 No. 246 P. 1-26

Ground-state properties of bosons interacting via inverse square potential (three dimensional Calogero-Sutherland model) are analyzed. A number of quantities scale with the density and can be naturally expressed in units of the Fermi energy and Fermi momentum multiplied by a dimensionless constant (Bertsch parameter). Two analytical approaches are developed: the Bogoliubov theory for weak and ...

Added: October 22, 2018

Chertenkov V., Shchur L., Journal of Physics: Conference Series 2021 Vol. 1740 P. 1-5

We formulate the problem of the universality class investigation using machine learning. We chose an example of the universality class of the two-dimensional 4-state Potts model. There are four known models within the universality class – the 4-state Potts model, the Baxter-Wu model, the Ashkin-Teller model, and the Turban model. All four of them together ...

Added: February 19, 2021

Yury A. Budkov, Petr E. Brandyshev, Nikolai N. Kalikin, Soft Matter 2023 Vol. 19 P. 3281-3289

Based on the random phase approximation, we develop a molecular theory of self-coacervation in zwitterionic polymer solutions. We show that the interplay between the volume interactions of the monomeric units and electrostatic correlations of charged groups on a polymer backbone can result in liquid-liquid phase separation (self-coacervation). We analyse the behavior of the coacervate phase ...

Added: April 18, 2023

Ilya D. Fedorov, Vladimir V. Stegailov, ChemPhysChem 2023 Vol. 24 No. 6 Article e202200730

The transition of warm dense fluid hydrogen from an insulator to a conducting state at pressures of about 20–400 GPa and temperatures of 500–5000 K has been the subject of active scientific research over the past few decades. However, various experimental and theoretical methods do not provide consistent results. In this work, we have applied the restricted ...

Added: January 31, 2023

O.I. Utesov, Syromyatnikov A. V., Physical Review B: Condensed Matter and Materials Physics 2018 Vol. 98 No. 18 P. 184406

We discuss theoretically frustrated Heisenberg spiral magnets in magnetic field H. We demonstrate that small
anisotropic spin interactions (single-ion biaxial anisotropy or dipolar forces) select the plane in which spins rotate
(spiral plane) and can lead to the spiral plane flop upon in-plane field increasing. Expressions for the critical
fields Hflop are derived. It is shown that measuring ...

Added: January 16, 2021

Garkul A., Stegailov V., Scientific Reports 2022 Vol. 12 No. 1 Article 13325

Unlike conventional first-order phase transitions, the kinetics of amorphous-amorphous transitions has been much less studied. The ultrasonic experiments on the transformations between low-density and high-density amorphous ice induced by pressure or heating provided the pressure and temperature dependencies of elastic moduli. In this article, we make an attempt to build a microscopic picture of these ...

Added: August 8, 2022

Blank M., Доклады Академии наук 2011 Т. 436 № 3 С. 295-298

In a recent paper we proposed a new model of the dynamics of
locally interacting particles (with a mean-field type interaction)
and proved that in the limit of weak interactions finite systems
of particles (or CML) may demonstrate both the synchronization,
and independent behavior (i.e. the phase transition takes place),
depending on fine properties of the interaction. Fundamental
technical limitation there ...

Added: November 26, 2014

Grigoriev S. V., Chubova N. M., Azarova L. A. et al., Annals of Physics 2022 Vol. 447 Article 169132

The cubic noncentrosymmetric structure of the B20 compounds produces the spin helix with the wave vector ks = D/J balanced by the competition of two interactions: the large ferromagnetic exchange interaction J and small antisymmetric Dzyaloshinskii–Moriya (DM) interaction D. The mixed Fe1−xCoxSi compounds demonstrate a switch of the sign of magnetic chirality in dependence of ...

Added: March 6, 2023

Budkov Y., Kolesnikov A. L., Journal of Physics: Condensed Matter 2020 Vol. 32 No. 36 Article 365001

In this paper we formulate a nonlocal density functional theory of inhomogeneous water. We model a water molecule as a couple of oppositely charged sites. The negatively charged sites interact with each other through the Lennard-Jones potential (steric and dispersion interactions), square-well potential (short-range specific interactions due to electron charge transfer), and Coulomb potential, whereas ...

Added: April 9, 2020

Shapiro D. S., Rubtsov A. N., Remizov S. V. et al., Physical Review A: Atomic, Molecular, and Optical physics 2019 Vol. 99 No. 6 Article 063821

The analysis of single-mode photon fluctuations and their counting statistics at the superradiant phase transition is presented. The study concerns the equilibrium Dicke model in a regime where the Rabi frequency, related to a coupling of the photon mode with a finite-number qubit environment, plays the role of the transition's control parameter. We use the ...

Added: October 29, 2021

Diana Sukhoverhova, Chertenkov V., Burovskiy E. et al., Lecture Notes in Computer Science 2023 Vol. 14389 P. 314-329

We analyze the Ising model and the Baxter-Wu model in two dimensions using deep learning networks trained to classify paramagnetic (PM) and ferromagnetic (FM) phases. We use the usual Metropolis Monte Carlo algorithm to create uncorrelated snapshots of spin states. The images used as training data are labeled as belonging to the PM state or ...

Added: November 9, 2023

Nechaev S. K., Gorsky A., Avetisov V. A. et al., Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2017 No. 96 P. 062309-1- 062309-14

We consider the canonical ensemble of multilayered constrained Erdos-Renyi networks (CERN) and regular random graphs (RRG), where each layer represents graph vertices painted in a specific color. We study the critical behavior in such networks under changing the fugacity, µ, which controls the number of monochromatic triads of nodes. The behavior of considered systems is ...

Added: October 20, 2017

Kolokolov I., Podivilov E., Cherepanov V., JETP Letters 2001 Vol. 74 No. 12 P. 596-599

The problem of the Berezinskii–Kosterlitz–Thouless transition in the highly frustrated XY kagomé antiferromagnet
is solved. The transition temperature is found. It is shown that the spin correlation function exponentially
decays with distance even in the low-temperature phase, in contrast to the order parameter correlation
function, which decays algebraically with distance. ...

Added: March 5, 2017

Valba O. V., Tamm M., Nechaev S., Physical Review Letters 2012 Vol. 109 P. 018102

We study the fraction f of nucleotides involved in the formation of a cactuslike secondary structure of random heteropolymer RNA-like molecules. In the low-temperature limit, we study this fraction as a function of the number c of different nucleotide species. We show, that with changing c, the secondary structures of random RNAs undergo a morphological transition:f(c)→1 for c≤ccr as the chain length n goes ...

Added: November 18, 2013