Characteristic phenomena in nanoscaled transverse Ising thin films with diluted surfaces

The phase diagrams and magnetizations of two nanoscaled thin films with a negative interlayer interaction and dilution at the surfaces, described by the transverse Ising model, are investigated by the use of the effective field theory with correlations. A lot of characteristic phenomena which heavily depend on the surface parameters can be found in them. In particular, the behaviors of a compensation point (or points) in these nanosystems with a negative interlayer interaction at the surfaces are examined by changing the transverse field and the physical parameters at the surfaces.     

Phase diagrams in an ultra-thin spin-1 transverse Ising film with bond or site dilution at surfaces

The phase diagrams of two nanoscaled thin films with bond and site dilutions at the surfaces, described by the spin-1 transverse Ising model, are investigated by the use of an effective field theory with correlations. A number of characteristic phenomena have been found in them, which are heavily dependent on the ratios (r = J₁/J and p = Ω_S/Ω, where J is the exchange interaction in the inner layer, J₁ is the exchange interaction between the surface and the next inner layer, Ω_S is the transverse field at the surfaces and Ω is the transverse field in the inner layer). Some of them have exhibited very similar behaviors found in the two spin-1/2 nanoscaled thin films with bond and site dilutions at the surfaces.     

Ferrimagnetic magnetizations of transverse Ising thin films with diluted surfaces

The temperature dependences of longitudinal and transverse magnetizations in transverse Ising thin films with diluted surfaces which are coupled antiferromagnetically to the bulk are studied by the use of the effective-field theory (EFT) with correlations. Novel features are obtained for the thermal variations of longitudinal magnetization, being different from those of the bulk ferrimagnetic materials, such as the possibility of two compensation points. They are depending on the thickness of a film and the surface dilution. These characteristic phenomena come from the competition between the surfaces and the bulk when the ratios of the physical parameters (transverse field and exchange interaction) between the surfaces and the bulk are selected as some large values.     

The possibility of a compensation point induced by a transverse field in transverse Ising nanoparticles with a negative core–shell coupling

The phase diagram and magnetizations of two 2D nanoparticles with a negative core–shell interaction, described by the transverse Ising model, are investigated by the use of the effective field theory with correlations. The behaviors of a compensation point in these nanosystems are examined by changing an applied transverse field. It is proved that a compensation point can be induced in the two nanosystems by applying a transverse field.     

The random transverse Ising thin film with decorated ferrimagnetic surfaces

The phase diagrams and magnetization curves of the random transverse Ising film with decorated spin-1 atoms on the surface are investigated by the use of an effective field method within the framework of a single cluster theory. In particular, the case in which decorated atoms at the surfaces are ordered ferrimagnetically is examined. The effects of the interactions, random transverse field at the surface and in the bulk, and film thickness are studied. A number of characteristic phenomena, such as the possibility of compensation points on the surfaces and in the film are found.     

Magnetic Phase Transitions in Quantum Ising Model with Annealed Antiferromagnetic Bond Randomness

The effect of annealed antiferromagnetic bond randomness on the phase transitions of the Quantum Ising Model (QIM) is studied by using mean-field renormalization group method. It is argued that bond randomness drastically alters multicritical phase diagram via transverse field. Multicritical points and coexistence region of ferromagnetic and antiferromagnetic case exist only at weak transverse field,.and are entirely eliminated at strong transverse field. The coexistence region diminishes in reducing the fluctuation interaction. This physical picture demonstrates that the competition between transverse field and exchange interaction and fluctuation interaction via bond randomness play an important role in generating multiphase structure. Another consequence of competition is that tricritical points of first-second order phase transitions are not entirely eliminated by bond randomness in two-dimensional QIM.     

Effect of Transverse Correlation Function on the Thermodynamic Quantities of Ferromagnetic Systems

The effect of transverse correlation between spins on the thermodynamic properties of ferromagnetic systems is investigated in details. Qualitatively, at finite temperature the transverse correlation reflects the short-range interaction between spins, so that lowers the internal energy and consequently raises the free energy. It also means the introduction of some ordering, and hence lowers the entropy. It is depressed by the field which forces the spins to turn to the field direction, so that it decreases with the field when temperature is fixed. The low-temperature expansion of the energy shows that the inclusion of the transverse correlation at least partly considers the interaction between spin waves.     

The possibility of re-entrant phenomena induced by a transverse field in ultra-thin transverse Ising films

The phase diagrams and temperature dependences of magnetizations in ultra-thin transverse Ising thin films are studied by the use of both the effective-field theory with correlations (EFT) and the mean-field theory (MFA). Novel features, such as the possibility of re-entrant phenomena, are obtained for the magnetic properties in such systems with a zero transverse field at the surfaces, when the EFT is applied to them, although such features could not be found from the use of the MFA. When the transverse field at the surfaces takes a finite value, however, the re-entrant phenomena could not be found from the both formulations of the EFT and the MFA. Similar phenomena are then obtained in the phase diagrams by using the MFA and the EFT.     

Ferroelectric phase transition of a finite alternating superlattice

The phase transition properties of ferroelectric supperlattice with finite alternating layers have been investigated by using the transverse Ising model within the mean field approximation. The effects of surface modification are introduced on the assumption that the exchange interaction and transverse field parameters on the top surface are different from those in other layers of the superlattice. The phase diagrams are described in two different ways. The results indicate that the features of the phase diagrams can be greatly modified by changing the transverse Ising model parameters.     

Field-induced nonmagnetic impurities interaction in the quantum Ising chain

We study static vacancies on a ferromagnetic spin-1/2 chain described by the transverse Ising model with second neighbor interactions at zero temperature. Using exact diagonalization techniques and applying a finite-size scaling approach, it is found that a strong magnetic field induces an effective potential of interaction between two vacancies that is attractive.     

Phase transition properties of ferroelectric thin films with two surface layers

The phase diagrams of ferroelectric thin films with two surface layers described by the transverse Ising model have been studied under the mean-field approximation. We discuss the effects of the exchange interaction and transverse field parameters on the phase diagrams. The results indicate that the phase transition properties of the phase diagrams can be greatly modified by changing the transverse Ising model parameters. In addition, the crossover features of the parameters from the ferroelectric dominant phase diagram to the paraelectric dominant phase diagram are determined for ferroelectric thin films with two surface layers.     

Electron paramagnetic resonance,acoustic EPR,and spontaneous spin-lattice relaxation at low temperatures

The effect of the coherent properties of the exciting field on the rate of spin-lattice relaxation is evaluated. It is shown that at low temperatures and high transverse components of the magnetic and elastic multipoles, relaxation is basically controlled by the interaction with the lattice of transverse oscillating components of the magnetization (or elastic moment), developing from interaction of the spin system with the changing field.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 7–12, August, 1973.     

On the possibility of natural formation of a transverse wave with a phase velocity lower than the velocity of light

The formation of a transverse wave with a phase velocity lower than the velocity of light, which can exist in an equilibrium plasma without a slow-wave structure in zero magnetic field, is described. It involves the transformation of a transverse wave with trapped electrons, traveling along the magnetic field, into a slow transverse wave after the removal of the magnetic field. During the evolution of the wave with trapped electrons, the magnetic induction decreases very slowly in the direction of the wave propagation. As a result, the velocity at which electrons are in resonant interaction with the wave increases; therefore, the electrons fall to the bottom of potential wells. Under the influence of the trapped electrons, the phase velocity of the wave decreases and becomes lower than the velocity of light. It becomes equal to the velocity at which the electrons are in resonance interaction with the wave at the instant when the magnetic field vanishes. It is demonstrated that a transverse wave with a velocity lower than the velocity of light can exist in an equilibrium plasma even after the magnetic field vanishes; in this case, the flow of trapped electrons serves as a slow-wave structure.     

Symmetry Breaking Induced Geometric Surfaces with Topological Curves in Quantum and Classical Dynamics of the SU(2) Coupled Oscillators

In the three‐dimensional (3D) transversely symmetric oscillator, there are plentiful degeneracies and gaps in the quantum energy spectrum as a function of the ratio of the transverse to longitudinal frequency. It is theoretically verified that while the SU(2) interaction destroys the original degeneracies, numerous new degeneracies and gaps emerge around the original degeneracies to form a similar fine energy spectrum. The classical trajectories at the emergent degeneracies are analyzed to be localized on the 3D parametric surfaces which are constituted by the topologically invariant curves in the transverse tomography. The quantum coherent states are exploited to develop the wave functions that correspond to the 3D geometric surfaces in classical dynamics. Furthermore, the wave structures of the stationary coherent states at small quantum numbers are explored and found to display peculiar patterns with symmetries related to classical trajectories.     

Epitaxy surface effect on the first-order phase transition properties in a ferroelectric thin film

By modifying the interchange interactions and the transverse fields on the epitaxy surface layer,this paper studies the phase transition properties of an n-layer ferroelectric thin film by the Fermi-type Green’s function technique based on the transverse Ising model with a four-spin interaction.The special attention is given to the effect of the epitaxy surface layer on the first-order phase transition properties in the parameter space constructed by the ratios of the bulk transverse field and the bulk four-spin interaction to the bulk two-spin interaction with the framework of the higher-order decoupling approximation to the Fermi-type Green’s function.The results show that the first-order phase transition properties will be changed significantly due to the modification of interchange interaction and transverse field parameters on the epitaxy surface layer.The dependence of the first-order phase transition properties on the thickness of ferroelectric thin films is also discussed.     

Nichtlineare Wechselwirkung elektromagnetischer Wellen im Plasma mit konstantem Magnetfeld

The nonlinear interaction of waves in anisotropic plasmas is considered. Solving the hydrodynamics equations with a n-th order perturbation procedure, an equation for the nonlinear electric field is derived. The n-th order current produced by interaction of waves with lower order is represented by means of a nonlinear tensor of conductivity, which is calculated for n = 2. It is shown, that a miced plasma wave with combination frequencies is excited as the result of interaction of two transverse (ordinary) waves propagating perpendicular to the magnetic field.     

High Frequency Current and Field Fluctuations in a Magnetized Plasma

The current density and electric field fluctuations at frequencies much above the ion plasma frequency are derived for a non-relativistic plasma of arbitrary density, using the Klimontovich approach. Both longitudinal and transverse components of the interaction forces between the electrons are taken into account. The error introduced by neglecting the transverse component is discussed.     

Solitons in a magnetized relativistic electron-positron plasma

Nonlinear equations for the interaction of the Langmuir wave field and the transverse electromagnetic field in the pulsar magnetosphere are derived. These equations take into account the modulational instability of plasma waves and its decay into two transversal waves.     

Entanglement in a two-spin system with long-range interactions

The quantum entanglement between two spins in the Ising model with an added Dzyaloshinsky–Moriya(DM) interaction and in the presence of the transverse magnetic field is studied. The exchange interaction is considered as a function of the distance between spins. The negativity as a function of magnetic field, exchange and DM interaction is calculated.The effect of the distance between spins is studied based on the negativity. In addition, the effect of the thermal fluctuation on the negativity is also investigated.     

Exact wave functions in a noncommutative field theory

We consider the nonrelativistic field theory with a quartic interaction on a noncommutative plane and compute the 2-->2 scattering amplitude within perturbative analysis to all orders. We regain the results of the perturbative analysis by finding the scattering and the bound state wave functions of the two particle Schrodinger equation. These wave functions unusually have two center positions in the relative coordinates, whose separation is transverse to the total momentum and scales linearly with its magnitude, exhibiting the stringy nature of the noncommutative field theory.