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Information × Registration Number 0223U001322, 0118U003376 , R & D reports Title Phase transitions and collective processes in superconductive, superfluid, magnetic and gravitation systems. popup.stage_title Head Pashitskii Ernst Anatolievich, д.ф.-м.н. Registration Date 27-01-2023 Organization Institute of Physics of National Academy of Sciences of Ukraine popup.description2 Phase transitions and collective effects in various systems on spatial scales ranging from microscopic to cosmological are theoretically investigated. New physical results are obtained: it is shown that a special type of collective charge density excitations – anisotropic acoustic plasmons – may appear in the superhydride LaH10, created under megabar pressure, and the influence of such plasmons on its “nearly room” critical temperature Tc is investigated; it is also shown that a moderate deviation from stoichiometry (the presence of hydrogen vacancies) can lead to a decrease in the Fermi level and emergence of additional hole "lenses" of the Fermi surface, thus facilitating the appearance of the acoustic plasmons, which contribute to the suppression of Coulomb repulsion and an increase in Tc; theoretical substantiation is given to the non-contact method of measuring of the critical current Jc and collective creep of magnetic flux in planar specimens of hard II-type superconductors (the loss-maximum method for nonlinear magnetic susceptibility), generalized for the case of open-faced pick-up coils; Cole–Cole diagrams for generalized nonlinear susceptibility for various relative sizes of specimen and flat spiral pick-up coil are plotted; the features of the energy spectra of domain walls and their structure in ordinary anisotropic and chiral ferrimagnets (cluster domain walls in the latter) near the spin compensation point, as well as the peculiarities of their movement (e.g., regions of instability) under the action of external force, are theoretically investigated using the collective variable approach; a possibility of similarity between gravitational and weak interactions, based on the fundamental idea of spontaneous symmetry breaking in a second-order phase transition, is explored; it is shown that short-range gravitational forces may exist on the Planck scale, due to the exchange of "superheavy" tensor bosons with mass generated through the Higgs-like mechanism Product Description popup.authors Galkina Olena Grygorivna Pashitskii Ernst Anatolievich Pentegov Vsevolod I. Semenov Oleksij Volodymyrovych popup.nrat_date 2023-01-27 Close