Nonequilibrium kinetics of the electron—phonon subsystem can give rise to electric and magneticplasticity effects in crystals in alternating electric and/or magnetic fields
V.I. Karas’^{ a, b},
V.I. Sokolenko^{ a}
^{a }National Scientific Centre ‘Kharkov Physicotechnical Institute’, ul. Akademicheskaya 1, Kharkov, 310108, Ukraine
^{b }V.N. Karazin Khar'kov National University, pl. Svobody 4, Khar'kov, 61077, Ukraine
Kinetic processes in magnetic crystals in a changing magnetic field and/or a pulsed electric field are studied theoretically, experimentally and numerically to establish the mechanisms by which they influence the structure and the mechanical, dissipative and magnetic characteristics of crystals. The specific materials studied are highly deformed ferrite pearlite steel 15Kh2NMFA and nickel. The paper presents a systematic kinetic analysis of the nonequilibrium dynamics of the electron—phonon subsystem of a magnetic crystal in an electric field. Our proposed method that underlies the analysis solves the system of Boltzmann equations for the electron and phonon distribution functions numerically without expanding the electron distribution function in a power series of the phonon energy. It is shown that the electronic subsystem excited by the electric field transfers energy to the phonon subsystem and thereby massively produces shortwave phonons which act strongly on lattice defects (such as point and linear ones and phase boundaries) and thus redistribute and decrease their density as well as eliminating damage, decreasing local peak stresses and reducing the degradation of structural properties. It is found that under the action of the induction electric field, the electron distribution function becomes nonequilibrium near the Fermi energy and, as a result of electron—phonon collisions, transfers significant energy to the phonon subsystem, resulting in a nonequilibrium phonon distribution function. Based on modified Granato—Lucke's and Landau—Gofman's models, it is shown, using the calculated phonon distribution function, that the effect of phonons on dislocations is much stronger than it would be in the case of thermodynamic equilibrium at the experimentally measured sample temperature of 12 K.
