Magnetocaloric Effect in Anisotropic Mixed Spin1/2–1 System: Pair Approximation Method

We use the Pair Approximation method to analyze the magnetic and magnetocaloric behaviors of diluted mixed spin S_A=1 and spin S_B=1/2 with the anisotropic Heisenberg model, on a cubic lattice with coordination number z=6. Our system is described in presence of an external magnetic field; the phase diagram and thermodynamic properties related to the concentration of magnetic atom(A or B) and the single ion anisotropy are constructed and discussed.Special attention is paid to magnetocaloric properties provided by isothermal entropy change as well as the cooling capacity. These cooling power keys are plotted and discussed as a function of interaction anisotropy and magnetic component concentration of two sublattices ions A and B. Numerical results show a double peak structure in the entropy change curve and the inverse magnetocaloric effect related to the presence of the negative single-ion anisotropy.     

Generalized Rashba Coupling Approximation to a Resonant Spin Hall Effect of the Spin–Orbit Coupling System in a Magnetic Field

We introduce a generalized Rashba coupling approximation to analytically solve confined two-dimensional electron systems with both the Rashba and Dresselhaus spin–orbit couplings in an external magnetic field. A solvable Hamiltonian is obtained by performing a simple change of basis, which has the same form as that with only Rashba coupling. Each Landau state becomes a new displaced-Fock state instead of the original Harmonic oscillator Fock state. Analytical energies are consistent with the numerical ones in a wide range of coupling strength even for a strong Zeeman splitting, exhibiting the validity of the analytical approximation. By using the eigenstates, spin polarization correctly displays a jump at the energy-level crossing point, where the corresponding spin conductance exhibits a pronounced resonant peak. As the component of the Dresselhaus coupling increases,the resonant point shifts to a smaller value of the magnetic field. In contrast to pure Rashba couplings, we find that the Dresselhaus coupling and Zeeman splittings tend to suppress the resonant spin Hall effect. Our method provides an easy-to-implement analytical treatment to two-dimensional electron gas systems with both types of spin–orbit couplings by applying a magnetic field.     

Spin—Other—Orbit Effect in Two—Mode Multiphoton Ionization

A previously unknown “spin-other-orbit” effect of photon modes is predicted by solving a Schrodinger-like equation for a non-relativistic electron interacting with a two-mode intense photon field propagating in two perpendicular directions.A multiphoton ionization experiment to test this effect is suggested.Transition rates which manifest this effect to be measured in the experiment are calculated and presented graphically.A detailed comparison between this effect and the well-known spin-other-orbit effect of electrons is included.     

Moment Method for Spin Analysis of the Pseudoscalar Pair Produced in the Radiative J/ψ Decay

The formalism and technique of the moment method for spin analysis of the boson X in J/ψ→γX,X→P₁P₂ are presented.The analysis technique is cited to study the spin of θ(1720) with Monte Carlo data samples.One finds that the spin of the boson X can be effectively determined by the moment method.As an example,the technique is used to measure the spin of the resonances in the low mass region of J/ψ→γK⁺K^－ channel at BES.It is found that the spin analysis strategy of the moment method is successful.     

The Mixed Spin-1/2 and Spin-1 Ising–Heisenberg Model in the Mean-Field Approximation: a New Approach

Thermodynamic properties of the mixed spin-1 and spin-1/2 Ising–Heisenberg model are studied on a honeycomb lattice using a new approach in the mean-field approximation to analyze the effects of longitudinal D_z and transverse D_x crystal fields. The phase diagrams are calculated in detail by studying the thermal variations of the order parameters, i.e., magnetizations and quadrupole moments, and compared with the literature to assess the reliability of the new approach. It is found that the model yields both second-and first-order phase transitions, and tricritical points. The compensation behavior of the model is also investigated for the sublattice magnetizations, and longitudinal and transverse quadrupolar moments. The latter type of compensation is observed in the literature but its possible importance is overlooked.     

Spin—Dependent Scattering Effects and Dimensional Crossover in a Quasi—Two—Dimensional Disordered Electron System

Two kinds of spin-dependent scattering effects (magnetic-impurity and spin-orbit scatterings) are investigated theoretically in a quasi-tow-dimensional (quasi-2D) disordered electron system.By making use of the diagrammatic techniques in perturbation theory,we have calculated the dc conductivity and magnetoresistance due to weak-localization effects,the analytical expressions of them are obtained as functions of the interlayer hopping energy and the characteristic times:elastic,inelastic,magnetic and spin-orbit scattering times.The relevant dimensional crossover behavior from 3D to 2D with decreasing the interlayer coupling is discussed,and the condition for the crossover is shown to be dependent on the aforementioned scattering times.At low temperature there exists a spin-dependent-scattering-induced dimensional crossover in this system.     

Mixed Former Effect：A Kind of COmposition Adjusting Method of Er—Doped Glass for Broadband Amplification

A compositional adjusting method called the mixed former effect is proposed to improve effectively optical properties such as the emission cross sectionk,the fluorescence full width at half maximum(FWHM)and the lifetime of the 4I13/2 level of Er-doped glass.A kind of Er-0doped bismuth-based glass illustrated high emission cross section (σe^p=0.66-0.90pm^2),large fluorescence FWHM(68-85nm),and relatively long lifetime of the ^4I13/2 level(Tm=1.6-4.3ms) using this method.A comparison of spectroscopic parameters shows that bismuth based glass is much better for broadband amplifiers than other glass hosts.     

A Simple Method to Generate Several Motional States in Two—Trapped Ions System

We propose a method to create several motional states imultancously in two -trapped ions.It relies on two standing wave lasers illuminating homogeneously both ions.By tuning the frequencies of the two standing waves to excite resonantly different sidebands of center-of -mass or breathing mode.several motional states.such as one-or two-mode squeezed states and their superpositions,and the beam-splitter output states,are generated.     

Electrons in Quasi-1D Waveguides with the Spin–Orbit Interaction: Manifestations of Additional Spin Symmetry

We consider quasi-one-dimensional electron waveguides with spin–orbit interaction, which are formed in quantum wells grown along arbitrary crystallographic directions. An analytic solution to the Schrödinger equation is obtained for systems with Hamiltonians possessing additional spin symmetry. It is shown that the dispersion curves for electrons, which correspond to different size-quantization modes, can intersect only when such symmetry exists. We analyze the structure of dips appearing on the dependences of the conductance of an inhomogeneous waveguide on the energy of carriers. It is shown that the width of the dips substantially depends on the waveguide orientation in the plane of the quantum well. In particular, it vanishes when the waveguide is formed along the direction of the “magic” vector of the initial 2D system.     

Spin Fluctuations and Concentration Magnetic Transitions in Chiral Helical Ferromagnets Fe1 – xCoxSi

Physics of the Solid State - The fluctuation theory is applied to the study of concentration transformations in Fe1 – xCoxSi disordered quasi-binary chiral helical...     

Temperature Dependence of Energy Gaps in Spin—1／2 Dimerized Heisenberg Chain

We present a method which combines a thermal coherent state approach with a self-consistent quantum theory to investigate the spin-1/2 dimerized antiferromagnetic Heisenberg chain.It is found that both excitation gaps between the ground state and two lowest excited modes,the triplet one-magnon excitation and the singlet two-magnon bound state decrease monotonically with increasing temperature.Our results are consitent with those obtained from the other approximations.     

Spin squeezing in Bose—Einstein condensates: Limits imposed by decoherence and non-zero temperature

We consider dynamically generated spin squeezing in interacting bimodal condensates. We show that particle losses and non-zero temperature effects in a multimode theory completely change the scaling of the best squeezing for large atom numbers. We present the new scalings and we give approximate analytical expressions for the squeezing in the thermodynamic limit. Besides reviewing our recent theoretical results, we give here a simple physical picture of how decoherence acts to limit the squeezing. We show in particular that under certain conditions the decoherence due to losses and non-zero temperature acts as a simple dephasing.     

Soliton Lattice State of Spin—1／2 Antiferromagnetic Chain in an External Magnetic Field

One-dimensional spin-1-2 anisotropic Heisenberg antiferromagnet in a longitudinal external magnetic field is studied using bosonization method and Gaussian wave functional techniques which take account of the spatial structure.The magnetization and the energy of the ground state which depend on the external magnetic field are calculated.For the case of anisotropic parameter △＞△0,increasing of the external magnetic field above the threshold value leads to the appearance of the soliton lattice state in the ground state,until to an another critical field where the ground state changes to the canted state phase.Therefore,with increasing external magnetic field,the ground state experiences four different phases successively,namely,antiferromagnetic Ising,soliton lattice state canted state,and magnetization saturated phases.When △＜△0,the soliton lattice state phase does not appear,with increasing external field,the paramagnetic phase smoothly evolves into the canted state phase,finally reaches magnetization saturated phase.     

Effect of Metallic Film in Diamond Growth from an Fe—Ni—C System at High Temperature and High Pressure

The metallic film surrounding a diamond single crystal,which plays an important role the diamond growth from and Fe-Ni-C system,has been successfully investigated by using transmission-electron microscopy(TEM),Raman layer(near diamond)of the film by TEM and Raman spectroscopy,but a parallel relationship exists between the(111) plane of γ-(Fe,Ni) and the (100) plane of (Fe2Ni)3C in this region.Compared with that of the film has an increase of 0.9V.According to the microstructures on the film obtained by the TEM.Raman spectra,and XPS,the catalytic mechanism of the film may be assumed as follows.In the surface layer of the film,iron and nickel atoms in the γ-(Fe,Ni) lattice can absorb carbon atoms in the (Fe,Ni)3C lattice and make them transform to an sp^3-like state.Then carbon atoms with the sp^3-like structure are separated from the (Fe,Ni)3C and stack on the growing diamond crystal.This study provides a direct evidence for the diamond growth from a metallic catlayst-graphite system under high temperature and high pressure.     

Martensitic Transformation,Magnetotransport Properties,and Magnetocaloric Effect in Ni47 – xMn42 + xIn11 Alloys (0 ≤ x ≤ 2)

Physics of the Solid State - The structure, electrical and magnetic properties of Ni47 – xMn42 + xIn11 (0 ≤ x ≤ 2) alloys upon changing the...     

H/D Isotope Effect in the Conductivity of CaZr1 – xScxO3 – α in Reducing Atmospheres

Physics of the Solid State - The ionic (proton and deuteron) conductivity of the system CaZr1 – xScxO3 – α (x = 0.03–0.20) is studied...     

Chaos and Fractals in a （2＋1）—Dimensional Soliton System

Considering that there are abundant coherent solitent soliton excitations in high dimensions,we reveal a novel phenomenon that the localized excitations possess chaotic and fractal behaviour in some(2 1)-dimensional soliton systems.To clarify the interesting phenomenon,we take the generalized(2 1)-dimensional Nizhnik-Novikov-Vesselov system as a concrete example,A quite general variable separation solutions of this system is derived via a variable separation approach first.then some new excitations like chaos and fractals are derived by introducing some types of lower-dimensional chaotic and fractal patterns.     

New Coherent Structures in the Generalized（2＋1）—Dimensional Nizhnik—Novikov—Veselov System

In high dimensions there are abundant coherent soliton excitations.From the known variable separation solutions for the generalized(2 1)-dimensional Nizhnik-Novikov-Veselov system.two kinds of new coherent structures in this system are obtained.Some interesting novel features of these structures are revealed.