Stochastic complete continuity property of operators connected with a Wiener process

We study properties of some linear and nonlinear operators which occur in the theory of stochastic differential and integral equations.Translated from Statisticheskie Metody Otsenivaniya i Proverki Gipotez, pp. 148–154, 1988.     

The influence of glass coating on the single domain wall potential in amorphous glass-coated Fe-based microwires

The effect of the glass coating on the single domain wall potential in amorphous glass-coated Fe-based microwire has been studied by the switching field distribution technique. The thermoactivated mechanism model is used to describe the thermally activated switching through the complex energy barrier in amorphous FeSiB microwires. Glass removal leads to the increase of the probability of the thermally activated switching pointing to the decrease of the energy barrier.     

Antiferromagnetic fluctuations in water-intercalated YBa2Cu3O6.8

Raman scattering by phononic and electronic excitations, as well as the magnetic susceptibility of water-intercalated YBa₂Cu₃O_6.8, has been studied. Direct evidence of the incorporation of OH^?-groups into the structure of the crystal has been obtained. The observed changes in the phonon spectrum and the appearance of the spectrum of antiferromagnetic fluctuations with an increased exchange coupling constant imply the localization of carriers and suppression of superconductivity. Change in the resonance behavior of the two-magnon scattering of light indicates the transformation of the electronic structure in crystallites absorbing water.     

Dynamics of the BiTeI lattice at high pressures

Raman measurements of the phonon spectrum of BiTeI at pressures of up to 20 GPa have been performed. A decrease in the linewidth of E² vibration by almost a factor of 2 with an increase in the pressure to 3 GPa has been detected. The frequencies of all four Raman active modes increase monotonically with the pressure. These lines are observed in spectra up to ～8 GPa. Sharp change in the spectrum occurs at pressures of 8–9 GPa, indicating a transition to the high-pressure phase, which holds up to 20 GPa. This transition is reversible and hardly has any hysteresis. A sample in the high-pressure phase is single crystal.     

Magnetocaloric effect and multifunctional properties of Ni–Mn-based Heusler alloys

The studies of magnetocaloric properties, phase transitions, and phenomena related to magnetic heterogeneity in the vicinity of the martensitic transition (MT) in Ni–Mn–In and Ni–Mn–Ga off-stoichiometric Heusler alloys are summarized. The crystal structure, magnetocaloric effect (MCE), and magnetotransport properties were studied for the following alloys: Ni₅₀Mn_50−xIn_x, Ni_50−xCo_xMn₃₅In₁₅, Ni₅₀Mn_35−xCo_xIn₁₅, Ni₅₀Mn₃₅In₁₄Z (Z=Al, Ge), Ni₅₀Mn₃₅In_15−xSi_x, Ni_50−xCo_xMn_25+yGa_25−y, and Ni_50–xCo_xMn_32−yFeyGa₁₈. It was found that the magnetic entropy change, ΔS, associated with the inverse MCE in the vicinity of the temperature of the magneto-structural transition, TM, persists in a range of (125-5) J/(kg K) for a magnetic field change ΔH=5 T. The corresponding temperature varies with composition from 143 to 400 K. The MT in Ni₅₀Mn_50−xIn_x (x=13.5) results in a transition between two paramagnetic states. Associated with the paramagnetic austenite-paramagnetic martensite transition ΔS=24 J/(kg K) was detected for ΔH=5 T at T=350 K. The variation in composition of Ni₂MnGa can drastically change the magnetic state of the martensitic phase below and in the vicinity of TM. The presence of the martensitic phase with magnetic moment much smaller than that in the austenitic phase above TM leads to the large inverse MCE in the Ni₄₂Co₈Mn_32−yFeyGa₁₈ system. The adiabatic change of temperature (ΔT_ad) in the vicinity of TC and TM of Ni₅₀Mn₃₅In₁₅ and Ni₅₀Mn₃₅In₁₄Z (Z=Al, Ge) was found to be ΔT_ad=−2 K and 2 K for ΔH=1.8 T, respectively. It was observed that |ΔT_ad|≈1 K for ΔH=1 T for both types of transitions. The results on resistivity, magnetoresistance, Hall resistivity in some In-based alloys are discussed.     

Collective and fractal properties of pion jets in the space of 4-velocities at intermediate energies

Experimental results obtained by studying collective and fractal properties of soft pion jets in the space of relative 4-velocities at intermediate energies are presented. The mean square of the distance between secondary particles and the jet axis is found to be significantly smaller in the case of pion-proton interactions at initial energies of about 3 GeV than in the case of hadron-hadron collisions at similar energies. This reduction leads to a power-law dependence of this quantity on the interaction energy in the energy range between about 2 and 4 GeV, and this makes it possible to estimate the lower boundary of the region where color degrees of freedom manifest themselves in pion-jet production. The cluster dimensions of pion jets in various reactions were obtained for the first time. Fractional values of this dimension may be a manifestation of fractal properties of pion jets. The change in the mean kinetic energy of particles in the jet and the change in the fractal dimension in response to the change in the collision energy is compatible with the assumption that color degrees of freedom come into play in pion-jet production at intermediate energies.

     

Associated φΛ0 production in the EXCHARM experiment

The features of the associated production of φ mesons with Λ⁰ hyperons in neutron-carbon interactions were investigated. The experiment was performed with the aid of the EXCHARM spectrometer at the Serpukhov accelerator in a neutron beam of energy in the interval 20–70 GeV. The differential cross section for inclusive associated φΛ⁰ production was measured.     

Associated production of ϕ mesons and neutral kaons in the EXCHARM experiment

The features of the associated production of ? mesons and neutral kaons are studied on the basis of data obtained at the EXCHARM spectrometer (Serpukhov accelerator) in neutron—carbon interactions at neutron-beam energies in the range 20–70 GeV. The cross section for the inclusive associated production of ? and K ⁰/-K ⁰ is obtained. The fraction of processes allowed by the Okubo-Zweig-Iizuka rule is estimated in the reactions of ?-meson inclusive production.