Modern Physics Letters B

The effects of electric and magnetic fields on the ground (1S-like) and excited (2S-like) states of an exciton in a narrow GaAs/Al_xGa_1-xAs parabolic quantum well are studied. The effective-mass approximation within a perturbation-variational scheme is adopted. We find that the hole-mass anisotropy and nonparabolicity of the conduction band significantly modify the electron properties in such structures in which the quantum confinement plays a fundamental role. The effect of the electric field on the spatial distribution of the electron and hole is also investigated. In the low field regime, the diamagnetic shift of the exciton energies is calculated.

Log Q versus log I_ph characteristics and laser enhanced mobility in the case of ZnS have been studied using a XeCl laser. The comparison of results in this case with multiphoton photoconductivity of other materials indicates two photon excitation from a lower valance band, wherefrom one-photon excitation is forbidden but two-photon excitation is allowed. Since the band-gap of ZnS is smaller than the photon energy of the XeCl laser, the result seems to be interesting.

The temperature dependence of the magnetic susceptibility of xFe₂O₃·(100-x)-[P₂O₅·CaO] glasses with 0<x≤50 mol% have been investigated. These data revealed that the valence states and the distribution of iron ions in the glass matrix depend on the Fe₂O₃ content. For the glasses with x≤1 mol% only Fe³⁺ ions are evidenced. In the case of the glasses with 3≤x≤35 mol% both Fe³⁺ and Fe² ions co-exist in the P₂O₅·CaO glass matrix, the Fe²⁺ ion content is higher than that of the Fe³⁺ ions for glasses with x≥10 mol%. For the glasses with x>35 mol%, the evaluated values of the μ_eff indicate either the presence of Fe⁺ ions or the coordination influence on the magnetic moment of iron ions, but the presence of small quantities of the antiferromagnetic or ferrimagnetic interactions between iron ions in studied temperature range cannot be excluded. The high temperature susceptibility results indicate that the iron ions are isolated or participate in dipole-dipole interactions for glasses with x≤35 mol% and are antiferromagnetically coupled for higher contents of Fe₂O₃.

The presence of magnetic moments in uranium atoms in some of U₂TSi₃, UTSi and U₂T₃Si (T is a 3d, 4d or 5d transition element) compounds is discussed in terms of the hybridization of s, p, d and f atomic orbitals. The hybridization strength in these ternary series of isostructural compounds was calculated using the semiquantitative band structure approach of Straub and Harrison. The prediction criterion for the presence of magnetic ordering, comparing the band width with a critical energy, seems to hold. The dominant influence of fd hybridization effects in the change of magnetic properties inside an isostructural group is in evidence.

The effect of the interaction between a disc and water-like particle on the wetting behavior of water-like phase between two discs has been investigated by free energy analysis and discontinuous molecular dynamic simulations. A detailed description for the partial wetting-complete wetting transition is provided and the analytical expressions describing the wetting behavior are obtained.

We construct a new kind of four-mode charge-related entangled state |q,k;n,m>_θϕ in Fock space, which can describe the process of photons, emitted from two energy levels in a optical cavity, being absorbed by another two levels simultanuously. The relation between |q,k;n,m>_θϕ and the four-mode entangled state |η,σ,τ>_θϕ (H.-Y. Fan et al., Mod. Phys. Lett.B16, 861 (2002)) is pointed out.