Probability distribution function for a solid with vacancies

Expression for probability distribution is got taking into account a presence and removal of degeneracy on the microstates. Its application allows to describe the process of melting of solids, as saltatory phase transition of the first kind without bringing in of concept of the order parameter.Comment: 3 pages, 3 figures; budget topic 0109U006004 of NAS of Ukrain

Conception of main local-strong-nonequilibriun state

A new conception of main local-strong-nonequilibrium state is proposed on the basis of development of the conception local equilibrium state. At list the conception is intended for description of evolution of internal defect structure in solids subjected severe external influences, for example, severe plastic deformation, radiation and so on, but can be developed on other closely related phenomena.Comment: 6 page

Vacancy theory of melting

The features of alternative approach of non-equilibrium evolution thermodynamics are shown on the example of theory of vacancies by opposed to the classic prototype of Landau theory. On this foundation a strict theory of the melting of metals, based on development of Frenkel ideas about the vacancy mechanism of such phenomena, is considered. The phenomenon of melting is able to be described as a discontinuous phase transition, while the traditional Frenkel's solution in the region of low-concentration of vacancies can describe such transition only as continuous one. The problem of limiting transition of shear modulus to zero values in the liquid state, as well as the problem of the influence of extended state of vacancies on their mobility, is discussed.Comment: 12 papges, 7 figure

Nonequilibrium evolution thermodynamics of vacancies

An alternative approach - nonequilibrium evolution thermodynamics, is compared with classical Landau approach. A statistical justification of the approach is carried out with help of probability distribution function on an example of a solid with vacancies. Two kinds of kinetic equations are deduced in terms of the internal energy and the modified free energy.Comment: 4 pages, 3 figure

Vortex mechanics in planar nano-magnets

A collective-variable approach for the study of non-linear dynamics of magnetic textures in planar nano-magnets is proposed. The variables are just arbitrary parameters (complex or real) in the specified analytical function of a complex variable, describing the texture in motion. Starting with such a function, a formal procedure is outlined, allowing a (non-linear) system of differential equations of motion to be obtained for the variables. The resulting equations are equivalent to Landau-Lifshitz-Gilbert dynamics as far as the definition of collective variables allows it. Apart from the collective-variable specification, the procedure does not involve any additional assumptions (such as translational invariance or steady-state motion). As an example, the equations of weakly non-linear motion of a magnetic vortex are derived and solved analytically. A simple formula for the dependence of the vortex precession frequency on its amplitude is derived. The results are verified against special cases from the literature and agree quantitatively with experiments and simulations.Comment: 7 pages, 1 figure, published versio

Four variants of theory of the second order phase transitions

Because of one-valued connection between the configurational entropy and the order parameter it is possible to present the theory of the second order phase transitions in terms of the configurational entropy. It is offered a variant of theory, in which the Nernst theorem is obeyed. Within the framework of heterogeneous model the phenomena of growth of level of fluctuations and their correlations are analyzed at transition of critical point as competitions of kinetic and relaxation processes in the conditions of proximity of two critical points.Comment: 9 pages, 10 figure

Spontaneous second order phase transition. Amorphous branch

A version of the second order phase transition theory, in which the Nernst theorem holds automatically, is proposed. The theory is constructed in terms of the order parameter and the (configurational) entropy. It faithfully reproduces the solutions of Landau theory as well as stable existence of ordered and disordered states and takes into account the existence of amorphous metastable states. Finally, phenomenon of growth of fluctuations magnitude due to random first order transitions between stable and metastable states as their energies approach each other at a critical point is analyzed.Comment: 4 page, 4 figure

Dynamical formation of a nonequilibrium subsystem under severe action

Formation of the nonequilibrium subsystem in dynamical processes during defect generation is simulated by means of molecular dynamics. A particular process of dissipation of the low-frequency acoustic emission into high-frequency equilibrium vibrations of lattice is studied numerically. Clear heuristic reasons are used to introduce different temperatures and entropies for equilibrium and nonequilibrium subsystems. Simple relaxation equation is proposed to describe time behavior of the nonequilibrium entropy.Comment: 4 pages, 4 figure

Two-dimensional topological solitons in small exchange-dominated cylindrical ferromagnetic particles

A general approach allowing to construct the magnetization distributions of arbitrary topological charge in small exchange-dominated cylindrical ferromagnetic particles is presented. The exchange energy functional is minimized by these distributions exactly. The magnetostatic energy is accounted partially, so that it facilitates a choice between the topologically equivalent exchange-only solutions. The resulting magnetization distributions can be easily generalized to a variety of non-circular cylindrical shapes by means of a conformal transformation. As an example a magnetic structures of a thin circular ferromagnetic cylinder both with centered and displaced magnetic vortex and of a finite Bloch domain wall in an elongated particle is given.Comment: 5 pages, 2 figures, RevTe

Two-dimensional topological solitons in soft ferromagnetic cylinders

A simple approach allowing to construct closed-form analytical zero-field magnetization distributions in cylindrical particles of a small thickness and an arbitrary shape (not necessarily circular) is presented. The approach is based on reduction of the non-linear Euler equations for magnetization vector field to the classical linear Riemann-Hilbert problem. The result contains all the distributions minimizing the exchange energy functional and the surface magnetostatic contribution exactly, except for the neighbourhood of topological singularities on the cylinder faces where the result is approximate. The completeness of the analysis permitted to find a new type of a topological soliton in the case of circular cylinder. Also, an example of magnetic vortex in a triangular cylinder is given to investigate the role of the particle corners.Comment: 3 pages, 2 figures, RevTeX 3 pages, 2 figures, RevTex (evaluated the integral (4) and added the equivalent formula (5), minor corrections to improve English, new Ref. [2]