[en] The quantum confined Stark effect (QCSE) of excitons in GaAs/AlAs corrugated lateral surface superlattices (CLSSLs) is calculated. Blue and red shifts in the exciton energies are predicted for the heavy- and light-excitons in the CLSSLs, respectively, comparing with those in the unmodulated quantum well due to the different effective hole masses in the parallel direction. Sensitive dependence of the QCSE on the hole effective mass in the parallel direction is expected because of the ''centre-of-mass'' quantization (CMQ) induced by the periodic corrugated interfaces of the CLSSLs. The effect of the CMQ on the exciton mini-bands and the localization of the excitons in the CLSSLs is discussed. (author)

[en] We construct the generators forming the exact SO(5) symmetry algebra for unified theory of Antiferromagnetism and Superconductivity. In the continuum limit of the standard d-wave factor g²(p) ∼ 1 the approximate SO(5) symmetry proposed by S.C. Zhang is recovered. (author)

[en] The concept of the semiquantum system, i.e. of a system which exhibits macroscopic quantum mechanical phenomena within the classical temperature range, is discussed and illustrated by numerous examples. Unusual long-range correlations of fundamentally quantum mechanical origin come into effect even at high temperatures and lead to a large variety of collective phenomena in such systems. Thermodynamics, transport, unique magnetic properties, and weakly damped collective modes in various semiquantum systems are described. Under certain conditions even a rarefied Maxwell-Boltzmann gas, the most classical matter in physics, can display a fundamentally quantum behaviour. The large magnitude of the effects in question makes the semiquantum systems very attractive for experimental study. The applications of the theory to condensed matter physics and materials science, atomic spectroscopy, molecular and electron beams, surface phenomena and neutron optics are considered. The most typical objectives for experimental study include helium and hydrogen systems, semiconductors, plasmas, conducting media with point and linear defects, layered electron structures, some classic fluids, spin-polarised systems, Rydberg atoms, etc. The present state of the art of and the new prospects for both theoretical and experimental studies are discussed

[en] Exact calculations of some universal quantities of two-dimensional statistical models in the vicinity of their fixed points are illustrated. (author)

[en] The mathematical model of nucleon spin relaxation time in the presence of dipole-dipole magnetic interaction is presented. The relaxation times as a temperature function are calculated using an expansion into spherical harmonics series. Results of calculations are presented

No abstract available

[en] The Kronig-Penney model is used to study the effect of nonlinear interaction on the transmissive properties of both ordered and disordered chains. In the ordered case, the nonlinearity can either localize or delocalize the electronic states depending on both its sign and strength but there is a critical strength above which all states are localized. In the disordered case, however, we found that the transmission decays as T∼L^-γ around the band edge of the corresponding periodic system. The exponent γ is independent of the strength of the nonlinearity in the case of disordered barrier potentials, while it varies with this strength for mixed potentials. (author)

[en] In the present letter, we investigate the ground state wave function for an explicit model of electrons in an external magnetic field with specific inter-particle interactions. The excitation states of this model are also given. (author)

[en] Strong compression effects are experimentally demonstrated by acting magnetic forces upon a cold cesium atom cloud. Atoms released from an optical molasses at a temperature of 5 μK experience during their fall a pulsed longitudinal force. Magnetic state selection occurs and time-of-flight spectrum compressions are obtained for definite experimental parameters. Corresponding spatial or velocity compressions are reported. (authors)

[en] The variation of single-particle spectral functions with doping is studied numerically within the t-J model. Results suggest that the corresponding self-energies change from local ones at the intermediate doping to strongly nonlocal ones for a weakly doped antiferromagnet. The nonlocality shows up most clearly in the pseudogap emerging in the density of states, due to the onset of short-range antiferromagnetic correlations. copyright 1999 The American Physical Society