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Registration Number

0221U105950, 0120U104857 , R & D reports

Title

Multiband electronic states: physics and applications

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Head

Kordiuk Oleksandr A., Доктор фізико-математичних наук

Registration Date

14-09-2021

Organization

State Research Institution "Kyiv Acedimic University"

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 A method for analyzing the photoemission spectra of multiband superconductors has been developed. It combines electronic structure modeling and convolution algorithms. Its application to cuprates allowed to confirm the spin-fluctuation nature of pairing, to model the instabilities of the electronic structure caused by the nesting of Van Hove singularities, and to demonstrate that this nesting mechanism well explains the antiferromagnetic ordering of cuprates in the "pseudogap" phase, where extremely small and large surfaces coexist. Taking into account the analogy with iron-based superconductors, this allowed us to propose an algorithm for finding superconductors with higher critical temperatures, but also to show that not only the magnitude of the energy gap but also the distribution of the superconducting order parameter in the momentum space of crystal is important. This allows us to reconcile the recommendations for the synthesis of new materials with higher TC with their practical application in quantum superconducting devices. A model describing the peculiarities of the dissociation of Abrikosov composite vortices in multiband superconductors has been developed. The dynamics of magnetic vortices entering a two-band superconductor and their motion during direct and alternating current flow through a superconducting tape has been modeled. It is shown that vortices from different zones enter the sample at different points in time and nonmonotonic time dependences of the magnetic flux for different values of the applied magnetic field are revealed. Under the alternating current flow, partial annihilation of vortices and anti -vortices with the effect of part of the vortices leaving the sample was detected. The occurrence of vortices of different signs through one edge of the sample at different points of time was also recorded.

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Bezghuba Volodymyr V
Bohachov Kyrylo H.
Boliasova Olha O.
Kasatkin Oleksandr L.
Kordyuk Alexander
Kutsyk Andrii M.
Pavlyuk Mykhaylo V.
Pokusinsʹkyy Anton O.
Pustovit Yurii V.
Shapovalov Andrii

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2021-09-14