2025, Neverov, V. D., Lukyanov, A .E., Krasavin, A. V., Vagov, A., Неверов, Вячеслав Дмитриевич, Лукьянов, Александр Евгеньевич, Красавин, Андрей Валерьевич

2024, Menushenkov, A. P., Ivanov, A., Neverov, V., Lukyanov, A., Krasavin, A., Yastrebtsev, A. A., Kovalev, I. A., Kuznetsov, A. V., Popov, V., Krymskaya, O., Менушенков, Алексей Павлович, Иванов, Андрей Анатольевич, Неверов, Вячеслав Дмитриевич, Лукьянов, Александр Евгеньевич, Красавин, Андрей Валерьевич, Ястребцев, Алексей Алексеевич, Кузнецов, Алексей Владимирович, Попов, Виктор Владимирович, Крымская, Ольга Александровна

2022, Zhumagulov, Y. V., Gulevich, D. R., Vagov, A., Perebeinos, V., Neverov, V. D., Lukyanov, A. E., Krasavin, A. V., Неверов, Вячеслав Дмитриевич, Лукьянов, Александр Евгеньевич, Красавин, Андрей Валерьевич

© 2022 American Physical Society.Second-harmonic generation (SHG) is a well-known nonlinear spectroscopy method to probe electronic structure, specifically, in transition metal dichalcogenide (TMDC) monolayers. This work investigates the nonlinear dynamics of a strongly excited TMDC monolayer by solving the time evolution equations for the density matrix. It is shown that the presence of excitons qualitatively changes the nonlinear dynamics leading, in particular, to a huge enhancement of the nonlinear signal as a function of the dielectric environment. It is also shown that the SHG polarization angular diagram and its dependence on the driving strength are very sensitive to the type of exciton state. This sensitivity suggests that SHG spectroscopy is a convenient tool for analyzing the fine structure of excitonic states.

2020, Неверов, В. Д., Неверов, Вячеслав Дмитриевич, Красавин Андрей Валерьевич

2019, Zumagulov, Y. V., Kashurnikov, V. A., Krasavin, A. V., Lukyanov, A. E., Neverov, V. D., Кашурников, Владимир Анатольевич, Красавин, Андрей Валерьевич, Лукьянов, Александр Евгеньевич, Неверов, Вячеслав Дмитриевич

The phase diagram of the two-dimensional two-orbital Hubbard model, which is widely used to describe high-temperature iron-based superconductors, is calculated in the electron doping region using the method of the variational cluster approximation. It is found that the coexistence of the antiferromagnetic and superconducting phases is realized in a wide range of electron doping values. In the superconducting phase, the order parameter has s(+/-) symmetry.

2025, ТОМАЕВА, М. А., НЕВЕРОВ, В. Д., КРАСАВИН, А. В., КАЛАШНИКОВ, А. В., ВАГОВ, А. В., КРОИТОРУ, М. Д., Калашников, Александр Викторович, Красавин, Андрей Валерьевич, Томаева, Муниса Альбертовна, Неверов, Вячеслав Дмитриевич

В работе рассмотрена зависимость сверхпроводящего эффекта близости от геометрии контакта сверхпроводник – нормальный металл. Показано существенное влияние кривизны контакта на закон затухания сверхпроводящих корреляций в нормальной области и определены характерные длины эффекта близости в случае чистого и грязного металла.

2024, Неверов, В. Д., Неверов, Вячеслав Дмитриевич, Красавин, А. В.

2022, Lukyanov, A. E., Kovalev, I. A., Neverov, V. D., Zhumagulov, Y. V., Krasavin, A. V., Лукьянов, Александр Евгеньевич, Неверов, Вячеслав Дмитриевич, Красавин, Андрей Валерьевич

BaBiO3 compound is known as an archetype example of a three-dimensional Holstein model with the realization of the charge-density wave state at half filling and the superconducting state when doped. Although many works are devoted to the study the electron-phonon interaction in BaBiO3, the influence of the electron-electron Hubbard interaction on the electronic structure in this system is still under investigation. In our work, we obtain analytical expression for the screened Coulomb potential, and along with the basis of ab initio-computed maximally localized Wannier orbitals, we quantitatively estimate the magnitude of the effective on-site Hubbard potential scrutinizing the effects of distortion of the crystal lattice. We show that a proper inclusion of the electron-electron interactions into the Holstein model significantly lowers the value of the underlying electron-phonon coupling. Finally, we find that the amplitudes of the repulsive electron-electron potential and its attractive counterpart mediated by the electron-phonon coupling are rather comparable. This may open a way for a realization of the intermediate phase of BaBiO3 in terms of the Holstein-Hubbard model.

2024, Neverov, V. D., Lukyanov, A. E., Krasavin, A. V., Vagov, A., Неверов, Вячеслав Дмитриевич, Лукьянов, Александр Евгеньевич, Красавин, Андрей Валерьевич

2019, Zhumagulov, Y. V., Krasavin, A. V., Lukyanov, A. E., Neverov, V. D., Yaroslavtsev, A. A., Menushenkov, A. P., Красавин, Андрей Валерьевич, Лукьянов, Александр Евгеньевич, Неверов, Вячеслав Дмитриевич, Менушенков, Алексей Павлович

© 2019, Pleiades Publishing, Inc.The band structure, densities of states, and O K-edge X-ray absorption spectra have been calculated by the density functional theory method for BaBiO3-based perovskite high-temperature superconductors at different potassium doping levels in the ground and optically excited states. It has been shown that this approach including local structural inhomogeneities caused by doping and optical irradiation allows the correct description of changes in the properties of the electron subsystem near the Fermi level. It has been shown that doping is accompanied by the appearance of hole carriers on the Bi6s−O2pσ*. hybridized orbital in agreement with the model of the electronic structure of bismuth-based high-temperature superconductors in terms of a spatially separated Fermi-Bose mixture. It has been found that the band structure for the excited state of the undoped compound is equivalent to the band structure of the tight binding model for a cubic lattice. The results are important for the preliminary analysis of time-resolved X-ray absorption spectra on an X-ray free electron laser at femtosecond optical excitation.