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Regular version of the site
Of all publications in the section: 50
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Article
Kolokolov I., Kakhidze A. Journal of Experimental and Theoretical Physics. 1991. Vol. 72. No. 4. P. 598-600.
Antiferromagnets with easy-plane anisotropy are proposed as axion detectors. It is shown that the response of the detector is proportional to the ratio of the Dzyaloshinskii field to the external magnetic field; this makes it possible to strengthen the bounds on the axion-electron interaction constant
Added: Mar 29, 2017
Article
Norman G., Starikov S., Stegailov V. Journal of Experimental and Theoretical Physics. 2012. Vol. 114. No. 5. P. 792-800.

The process of ablation of a gold target by femto- and picosecond laser radiation pulses has been studied by numerical simulations using an atomistic model with allowance for the electron subsystem and the dependence of the ion–ion interaction potential on the electron temperature. Using this potential, it is possible to take into account the change in the physical properties of the ion subsystem as a result of heating of the electron subsystem. The results of simulations reveal a significant difference between the characteristics of metal ablation by laser pulses of various durations. For ablation with subpicosecond pulses, two mechanisms of metal fracture related to the evolution of electronic pressure in the system are established.

Added: Mar 19, 2014
Article
Popova E., Vasil’ev A. N., Klimin S. A. et al. Journal of Experimental and Theoretical Physics. 2010. Vol. 111. No. 2. P. 204-208.
Added: Apr 12, 2012
Article
Klapwijk T. M., Ryabchun S. Journal of Experimental and Theoretical Physics. 2014. Vol. 119. No. 6. P. 997-1017.

An overview is presented of experiments on ballistic electrical transport in inhomogeneous super conducting systems which are controlled by the process of Andreev reflection. The initial experiments based on the coexistence of a normal phase and a superconducting phase in the intermediate state led to the concept itself. It was followed by a focus on geometrically inhomogeneous systems like point contacts, which provided a very clear manifestation of the energy and direction dependence of the Andreev reflection process. The point contacts have recently evolved towards the atomic scale due to the use of mechanical breakjunctions, revealing a very detailed dependence of Andreev reflection on the macroscopic phase of the superconducting state. In presentday research, the superconducting in homogeneity is constructed by clean room technology and combines superconducting materials, for example, with lowdimensional materials and topological insu lators. Alternatively, the superconductor is combined with nanoobjects, such as graphene, carbon nano tubes, or semiconducting nanowires. Each of these “inhomogeneous systems” provides a very interesting range of properties, all rooted in some manifestation of Andreev reflection.

Added: Mar 27, 2015
Article
Samoilov I. S., Baev V. P., Timofeev A. et al. Journal of Experimental and Theoretical Physics. 2017. Vol. 124. No. 3. P. 496-504.

Dusty plasma structures in glow discharge in helium in the temperature range of 5–300 K are investigated experimentally. We have described the experimental setup that makes it possible to continuously vary the temperature regime. The method for experimental data processing has been described. We have measured interparticle distances in the temperature range of 9–295 K and compared them with the Debye radius. We indicate the ranges of variations in experimental parameters in which plasma–dust structures are formed and various types of their behavior are manifested (rotation, vibrations of structures, formation of vertical linear chains, etc.). The applicability of the Yukawa potential to the description of the structural properties of a dusty plasma in the experimental conditions is discussed.

Added: Jun 7, 2017
Article
Kolokolov I., Turitsyn K. S. Journal of Experimental and Theoretical Physics. 2002. Vol. 94. No. 6. P. 1193-1200.
For the field u(x, t) governed by the Burgers equation with a thermal noise, short-time asymptotics of multipoint correlators are obtained. Their exponential parts are independent of the correlator number. This means that they are determined by a single rare fluctuation and exhibit the intermittency phenomenon
Added: Feb 25, 2017
Article
Kolokolov I., Chertkov M. Journal of Experimental and Theoretical Physics. 1994. Vol. 79. No. 5. P. 824-832.
Using the functional integration method we compute exactly the time-dependent correlation functions of local spins in a finite quantum Heisenberg magnet with a position-independent exchange between spins. Explicit expressions for such correlation functions for an arbitrary number (N) of spins in the cluster and for all temperatures are presented. The spin correlation function for a cluster placed in an external time-dependent magnetic field is obtained under the same conditions. At large N the correlation function is found to have a Gaussian bump and a nonvanishing tail at large times. It is in good agreement with the finite-time domain of the experimental curve. A possible application of the exact results, which form a starting dynamical mean-field approximation for long-range magnets and an accompanied physical picture, are discussed
Added: Mar 28, 2017
Article
Krasnikova J., Glazkov V., Soldatov T. A. Journal of Experimental and Theoretical Physics. 2017. Vol. 125. No. 3. P. 476-479.

We have measured antiferromagnetic resonance (AFMR) frequency-field dependences for aluminum–manganese garnet Mn3Al2Ge3O12 at frequencies from 1 to 125 GHz and fields up to 6 T. There are three AFMR modes for all orientations, their zero field gaps are about 40 and 70 GHz. Andreev–Marchenko hydrodynamic theory [7] well describes experimental frequency–field dependences. We have observed hysteresis of resonance absorption as well as history dependence of resonance absorption near gap frequencies below 10 kOe in all three measured field orientations, which are supposedly due to the sample domain structure. Observation of the AFMR signal at the frequencies from 1 to 5 GHz allows to estimate repulsion of nuclear and electron modes of spin precession in the vicinity of spin-reorientation transition at H || [100].

Added: Nov 20, 2017
Article
Norman G., Saitov I., Stegailov V. Journal of Experimental and Theoretical Physics. 2015. Vol. 120. No. 5. P. 894-904.

Within electron density functional theory (DFT), the reflectance of radiation from shock-compressed xenon plasma is calculated. The dependence of the reflectance on the frequency of the incident radiation and on the plasma density is considered. The Fresnel formula is used. The expression for the longitudinal dielectric tensor in the long-wavelength limit is used to calculate the imaginary part of the dielectric function (DF). The real part of the DF is determined by the Kramers-Kronig transformation. The results are compared with experimental data. An approach is proposed to estimate the plasma frequency in shock-compressed xenon. © 2015, Pleiades Publishing, Inc.

Added: Sep 7, 2015
Article
Kolokolov I. Journal of Experimental and Theoretical Physics. 1986. Vol. 64. No. 6. P. 1373-1375.
Added: Mar 31, 2017
Article
Kolokolov I., Podivilov E. V. Journal of Experimental and Theoretical Physics. 1989. Vol. 68. No. 1. P. 119-125.
Added: Mar 30, 2017
Article
Aseeva N.V., Gromov E.M., Tyutin V. V. Journal of Experimental and Theoretical Physics. 2015. Vol. 121. No. 6. P. 955-960.

The dynamics of high-frequency field solitons is considered using the extended nonhomogeneous nonlinear Schrodinger equation with induced scattering from damped low-frequency waves (pseudoinduced scattering). This scattering is a 3D analog of the stimulated Raman scattering from temporal spatially homogeneous damped low-frequency modes, which is well known in optics. Spatial inhomogeneities of second-order linear dispersion and cubic nonlinearity are also taken into account. It is shown that the shift in the 3D spectrum of soliton wavenumbers toward the short-wavelength region is due to nonlinearity increasing in coordinate and to decreasing dispersion. Analytic results are confirmed by numerical calculations.

Added: Aug 18, 2015
Article
Kolokolov I., Lebedev V., Sizov G. Journal of Experimental and Theoretical Physics. 2011. Vol. 140. No. 2. P. 387-400.

We analyze magnetic kinematic dynamo in a conducting fluid where the stationary shear flow is accompanied by relatively weak random velocity fluctuations. The diffusionless and diffusion regimes are described. The growth rates of the magnetic field moments are related to the statistical characteristics of the flow describing divergence of the Lagrangian trajectories. The magnetic field correlation functions are examined, we establish their growth rates and scaling behavior. General assertions are illustrated by explicit solution of the model where the velocity field is short-correlated in time.  

Added: Feb 2, 2017
Article
Kolokolov I., L'vov V. S., Cherepanov V. Journal of Experimental and Theoretical Physics. 1984. Vol. 59. No. 5. P. 1131-1139.
Added: Mar 31, 2017
Article
Arseyev P., Maslova N. Journal of Experimental and Theoretical Physics. 2016. Vol. 122. No. 3. P. 402-411.

It is shown how the general formulas of the nonequilibrium diagram technique can be used in problems of tunnel planar structures described in the effective mass approach. The relation between such a “continual” approach and the tunneling Hamiltonian method is established, and the applicability conditions for this method are determined. The effects beyond the applicability limits of the tunneling Hamiltonian method, which can be described by the continual approach, are considered.

Added: Jul 7, 2016
Article
Arseyev P., Mantsevich V., Maslova N. Journal of Experimental and Theoretical Physics. 2014. Vol. 118. No. 1. P. 136-147.

We found analytical solution for the time evolution of localized electron density in a system of two coupled single-level quantum dots (QDs) connected with continuous spectrum states in the presence of Coulomb interaction. This solution takes into account QD electrons correlation functions of all orders neglecting any correlations between localized and conduction electron filling numbers. We demonstrated that several time scales with the strongly different relaxation rates appear in the system for a wide range of the Coulomb interaction value. We revealed that specific non monotonic behavior of charge relaxation in QD takes place due to Coulomb correlations. We also found out that besides the usual charge oscillations with the period determined by the detuning between the energy levels of the QDs a new effect of period doubling appears in the presence of Coulomb interaction at particular range of the system parameters.

Added: Oct 28, 2014
Article
Kovaleva N., K.I. Kugel, Potůčhek Z. et al. Journal of Experimental and Theoretical Physics. 2016. Vol. 122. No. 5. P. 890-901.

In magnetic compounds with Jahn–Teller (JT) ions (such as Mn3+ or Cu2+), the ordering of the electron or hole orbitals is associated with cooperative lattice distortions. There the role of JT effect, although widely recognized, is still elusive in the ground state properties. Here we discovered that, in these materials, there exist excitations whose energy spectrum is described in terms of the total angular momentum eigenstates and is quantized as in quantum rotors found in JT centers. We observed features originating from these excitations in the optical spectra of a model compound LaMnO3 using ellipsometry technique. They appear clearly as narrow sidebands accompanying the electron transition between the JT split orbitals on neighboring Mn3+ ions, displaying anomalous temperature behavior around the Néel temperature TN ≈ 140 K. We present these results together with new experimental data on photoluminescence found in LaMnO3, which lend additional support to the ellipsometry implying the electronic-vibrational origin of the quantum rotor orbital excitations. We note that the discovered orbital excitations of quantum rotors may play an important role in many unusual properties observed in these materials upon doping, such as high-temperature superconductivity and colossal magnetoresistance.

Added: Feb 19, 2017
Article
Kolokolov I., Lebedev V., Stepanov M. Journal of Experimental and Theoretical Physics. 1999. Vol. 88. No. 3. P. 506-516.
We consider advection of a passive scalar u (t,r) by an incompressible large-scale turbulent flow. In the framework of the Kraichnan model all PDF’s ~probability distribution functions! for the single-point statistics of u and for the passive scalar difference u (r1)2u (r2) ~for separations r12r2 lying in the convective interval! are found.
Added: Mar 8, 2017
Article
Glazkov V. Journal of Experimental and Theoretical Physics. 2019. Vol. 128. No. 3. P. 464-476.

We discuss magnetization curves of a toy-model trigonal and tetrahedral clusters. Nonlinearity of magnetization with local minimum of differential susceptibility resembling known magnetization plateaus of triangular-lattice and pyrochlore lattice antiferromagnets is observed at intermediate temperature range JT ≲ Θ (here, J is the exchange coupling constant and Θ is a Curie–Weiss temperature). This behavior is due to increased statistical weight of the states with intermediate total spin of the cluster, which is related to the “order-by-disorder” mechanism of plateau stabilization of a macroscopic frustrated magnet.

Added: Jun 5, 2019
Article
Khomskii D. I., K.I. Kugel, Sboychakov A. O. et al. Journal of Experimental and Theoretical Physics. 2016. Vol. 122. No. 3. P. 484-498.

We analyze the role of local geometry in the spin and orbital interaction in transition metal compounds with orbital degeneracy. We stress that the tendency observed in the most studied case (transition metals in O6 octahedra with one common oxygen—common corner of neighboring octahedra—and with ~180° metal–oxygen–metal bonds), that ferro-orbital ordering renders antiferro-spin coupling and, vice versa, antiferro-orbitals give ferro-spin ordering, is not valid in the general case, in particular, for octahedra with a common edge and with ~90° M–O–M bonds. Special attention is paid to the “third case,” that of neighboring octahedra with a common face (three common oxygens), which has largely been disregarded until now, although there are many real systems with this geometry. Interestingly enough, the spin-orbit exchange in this case turns out to be simpler and more symmetric than in the first two cases. We also consider, which form the effective exchange takes for different geometries in the case of strong spin–orbit coupling.

Added: Feb 18, 2017
Article
Kolokolov I., L'vov V. S., Cherepanov V. Journal of Experimental and Theoretical Physics. 1983. Vol. 57. No. 3. P. 605-613.
Added: Mar 31, 2017