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Solid-state synthesis is widely used in exploratory research to study various structural modifications that affect the properties (critical temperature, critical current density, irreversibility field, etc.) of superconductors. The popularity of this method is due to its relative simplicity and availability of the necessary equipment. Combining solid-state synthesis and top-seeded melt growth allows us to increase the grain size in a Tm- and Nd-based 1-2-3 superconductor. Samples with a grain size up to 0.1 mm have been obtained. X-ray diffraction, scanning electron microscopy and magnetization measurements have been used for investigating this superconducting material. The magnetization width {\Delta}M has increased significantly in the synthesized samples. However the temperature dependence of the intragrain critical current density and the pinning force scaling give evidences that the pinning mechanism in the obtained superconductor is essentially the same as in polycrystalline superconductors synthesized by standard solid-state technology. The increase in grain size in the synthesized samples is the main reason for the high values of {\Delta}M., Comment: 12 pages, 7 figures

HoFe1-xMnxO3 (0 < x < 1) single crystals have been grown by the optical floating zone technique. A structural transition from the orthorhombic to hexagonal modification has been established in the crystals in the concentration range of 0.7-0.8, which has been confirmed by the X-ray diffraction data. For a series of the rhombic crystals, the room-temperature Mossbauer study and magnetic measurements in the temperature range of 4.2-1000 K have been carried out. It has been observed that, with an increase in the manganese content in the samples, the temperature of the spin-reorientation transition increases significantly: from 60 K in the HoFeO3 compound to room temperature in HoFe0.6Mn0.4O3. The magnetic measurements have shown that, upon substitution of manganese for iron, the magnetic orientational type transition changes from a second-order transition (AxFyGz -> CxGyFz) to first-order one (AxFyGz -> GxCyAz) with a weak ferromagnetic moment only in the b direction (for Pnma notation). The growth of the spin-reorientation transition temperature has been attributed to the change in the value of the indirect exchange in the iron subsystem under the action of manganese, which has been found when studying the Mossbauer effect in the HoFe1-xMnxO3 (x < 0.4) compound.

A misalignment of anisotropic crystallites causes small values of anisotropy and decreases the critical current density of textured polycrystalline superconductors. To relate the crystallite misalignment and out-plane anisotropy, the magnetic properties of the textured Bi2223 polycrystalline superconductor were investigated. A distribution of orientation angles of crystallites was determined using different data: scanning electron microscopy images and hysteresis magnetization loops when an external magnetic field was applied at different angles with respect to the texturing plane of the sample. It was demonstrated that the standard deviation of the distribution and the magnetic disorder angle of crystallites in textured samples can be determined from the magnetization data in perpendicular directions. These data may be either the irreversible magnetization measured for two different orientations of the sample or the simultaneously measured magnetization projections parallel and perpendicular to the magnetic field., Comment: 11 pages, 6 figures

Structural, magnetic and multiferroic properties of single crystals of Dy$_{1-x}$Ho$_x$MnO$_3$ ($x = 0, 0.2$) were investigated by the different methods of polarized and classical neutron diffraction and macroscopic methods in order to determine the effect of Ho doping on the magneto-electric behavior of the title compounds. It is shown that substitution by Ho of 20% on the position of Dy do not change overall crystal symmetry of compound. It remains of Pnma type for both compositions down to the very low temperatures. Magnetic ordering do not change the crystal structure. Precise magnetic order and it detailed temperature and field evolution both in the pristine and substituted compounds we determined using single crystal neutron diffraction and magnetization measurements. The results show a complex interplay between transition metal and rear earth magnetic sub lattices leading to so-called "Mn-controlled" and "Dy-controlled" magnetic states. Using polarized neutron diffraction 3D character of rear earth magnetic order in Dy$_{0.8}$Ho$_{0.2}$MnO$_3$ in contract to DyMnO$_3$ and occurrence of the chiral type magnetic structure on Mn subsystem could be revealed. The influence of the external electric field on the magnetic chirality could be directly evidenced, proving strong magneto-electric coupling in multiferroic phase. The study of the electric polarization under similar temperatures and fields on the same samples provides the direct correlation between the results of the microscopic and macroscopic investigations., Comment: 26 pages, 12 figures, 3 tables

Neutron diffraction studies of HoFeO$_3$ single crystal were performed under external magnetic fields. The interplay between the external magnetic field, Dzyaloshinsky-Moria antisymmetric exchange and isotropic exchange interactions between Fe and Ho sublattice and inside Fe sublattice provides a rich phase diagram. As the result of the balance of exchange interactions inside crystal and external magnetic field we found 8 different magnetic phases, produced or suppressed by the field., Comment: 15 pages, 11 figures, 4 tables

Light sterile neutrinos contributions both for active neutrinos oscillations and neutrinoless double beta decay characteristics are estimated in the framework of the phenomenological model with three active and three sterile neutrinos assuming the Majorana nature of neutrino. Appearance and survival probabilities for active neutrinos with contributions of eV-sterile neutrinos in application to the short-baseline anomalies in neutrino data are obtained at the same test values of the model parameters. Modified graphical dependences for the survival probability of electron neutrinos/antineutrinos and the probability of appearance of electron neutrinos/antineutrinos in muon neutrino/antineutrino beams as functions of distance and other model parameters at different neutrino energies, and also as functions of the ratio of the distance to the neutrino energy are presented. A significant difference was found between the probability curves of the considered neutrino model and the simple sinusoidal curves of the neutrino model with one sterile neutrino. Effective electron neutrino masses for the beta decay and the neutrinoless double beta decay are estimated with account of eV-sterile neutrinos contributions. Besides, the two-neutrino double beta decay characteristics for selenium-82 are calculated. These findings can be used for interpretation and prediction of results of ground-based experiments on search for the sterile neutrinos as well as the neutrinoless double beta decay., Comment: 18 pages, 4 figures

The recent experimental data on mixing angles for quarks and neutrino have been discussed. Quarks mixing angles are calculated in the phenomenological approach of Fritzsch-Scadron-Delbourgo-Rupp (FSDR approach) using mass values of light and heavy constituent quarks. The neutrino mixing angles have been calculated with the high degree of precision with the help of the hypothesis of quarks and neutrino mixing angles complementarity, the results obtained do not contradict with the present experimental data., Comment: 10 pages, typos corrected, short remark about evaluated uncertainties is inserted

The systematic study of (anti-)neutrino accompanied beta^-beta^-, beta^+beta^+ decays and beta^+/EC, EC/EC electron captures is performed under the assumption of single intermediate nuclear state dominance. The corresponding half-lives are evaluated both for transitions to the ground state as well as to the 0^+ and 2^+ excited states of final nucleus. It is stressed that the hypothesis of single state dominance can be confirmed or ruled out by the precision measurements of the differential characteristics of the 2nbb-decays of 100Mo and 116Cd as well as beta^+/EC electron capture in 106Cd, 130Ba and 136Ce., Comment: 17 pages including 3 eps figure

We investigate neutrino flux induced double beta transitions in targets built of Cd112, Cd114, Cd116 and O18 isotopes. In addition to known beta^- beta^- channel we consider new beta^- beta^+ and beta^- beta^+ gamma modes of the neutrino induced double beta process. A possibility of detection of the solar neutrinos via the induced double beta transitions of interest is discussed. We note that the beta^- part of the solar neutrino induced beta^- beta^+ process in O18 was already discussed in Ref. [9,10] in connection with a possible influence of high energy electron production of this origin on the SuperKamiokande results., Comment: 5 pages, LaTeX. Talk presented by S. V. Semenov on International Workhop on Non-Accelerator New Physics (NANP'01), Dubna, Russia, June 2001, to be published in Phys. Atom. Nucl. (2002)

The detection of solar-neutrinos of different origin via induced beta beta process of Mo100 is investigated. The particular counting rates and energy distributions of emitted electrons are presented. A discussion in respect to solar-neutrino detector consisting of 10 tones of Mo100 is included. Both the cases of the standard solar model and neutrino oscillation scenarios are analyzed. Moreover, new beta^- beta^+ and beta^-/EC channels of the double-beta process are introduced and possibilities of their experimental observation are addressed., Comment: 8 pages, LaTeX, 2 postscript figures, Talk presented by P. Domin on the workshop MEDEX'01 (Prague, June, 2001), to appear in Czech. J. Phys. 52 (2002)

In the framework of the relativistic independent quark model the parameters of the QCD-motivated static potential and the quark masses are calculated on the basis of the $1^{--}$ meson mass spectra. The value of the confining potential coefficient is found to be ($0.197\pm 0.005) GeV${}^2$. for quark- antiquark interaction independently on their flavours. The dependence of the quasi-Coulombic potential strength on the interaction distance are consistent with the QCD-motivated behaviour. The $q\bar q$-separations are evaluated and the $e^+e^-$ decay widths are estimated with the help of relativistic modification of the Van Royen-Weisskopf formula., Comment: 10 pages, LaTex; added references for the beginning, changed the last paragraph at the end, made a few stylistic corrections

The hypothesis of the single state dominance (SSD) in the calculation of the two-neutrino double beta decay of Mo100 is tested by exact consideration of the energy denominators of the perturbation theory. Both transitions to the ground state as well as to the 0+ and 2+ excited states of the final nucleus Ru100 are considered. We demonstrate, that by experimental investigation of the single electron energy distribution and the angular correlation of the outgoing electrons, the SSD hypothesis can be confirmed or ruled out by a precise two-neutrino double beta decay measurement (e.g. by NEMO III collaboration)., Comment: 13 pages, RevTex, 1 figure

The universality hypothesis for scalar confining potential between quark and antiquark with different flavours is confirmed within 0.05 level of relativity errors., Comment: 12 pages (18kb), latex, no figures