Персона:
Кузнецов, Алексей Владимирович

Организационные подразделения

Организационная единица

Институт лазерных и плазменных технологий

Стратегическая цель Института ЛаПлаз – стать ведущей научной школой и ядром развития инноваций по лазерным, плазменным, радиационным и ускорительным технологиям, с уникальными образовательными программами, востребованными на российском и мировом рынке образовательных услуг.

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Кузнецов

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Алексей Владимирович

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Только метаданные
Anisotropy of the Hall Effect in the Paramagnetic Phase of Ho0.8Lu0.2B12 Cage Glass
(2021) Khoroshilov, A. L.; Azarevich, A. N.; Bogach, A. V.; Glushkov, V. V.; Kuznetsov, A. V.; Кузнецов, Алексей Владимирович
© 2021, Pleiades Publishing, Inc.Detailed measurements of the Hall effect in the paramagnetic phase of Ho0.8Lu0.2B12 antiferromagnet at the magnetic field up to 80 kOe in the temperature range of 1.9–300 K have been performed. It has been found that the transition to the cage glass phase (T < T * ~ 60 K) is accompanied by the appearance of a positive Hall resistance component in addition to that corresponding to the negative Hall effect. The amplitude and angular dependence of the former depend on the magnitude and direction of the applied magnetic field with respect to the crystallographic axes. The revealed anisotropy of the Hall effect in Ho0.8Lu0.2B12 is attributed to the interaction of charge carriers with dynamic charge stripes.
Только метаданные
Magnetic susceptibility of pyrochlores R2Ti2O7: R = Gd, Dy, Tb
(2020) Kuznetsov, A. V.; Churkin, O. A.; Ivanov, A. A.; Popov, V. V.; Alekseev, P. A.; Menushenkov, A. P.; Кузнецов, Алексей Владимирович; Чуркин, Олег Алексеевич; Иванов, Андрей Анатольевич; Попов, Виктор Владимирович; Алексеев, Павел Александрович; Менушенков, Алексей Павлович
© 2019We present the study of magnetic susceptibility of pyrochlores Gd2Ti2O7, Dy2Ti2O7 and Tb2Ti2O7 which belong to frustrated magnets. The temperature dependence of the susceptibility χ(T) of powder samples was measured in the temperature range from 4.2 to 300 K and analyzed in the framework of mean field approximation taking into account both crystal field effects and anisotropy of the exchange interaction. We developed a simple approach allowing us to estimate interaction energies of magnetic ions from χ(T) dependences and data on wave functions of the crystal-field states of the ions using a minimum number of fitting parameters. We revealed a strong anisotropy of the exchange interaction in the paramagnetic state of Gd2Ti2O7 and obtained nearest-neighbor effective bond energies of the magnetic ions in Tb2Ti2O7 and Dy2Ti2O7 which are in good agreement with the temperatures of formation of the spin-ice state in these compounds.
Только метаданные
Magnetization of Crystalline and Amorphous Phases of R(2)Ti(2)O(7)and R2Zr2O7(R = Gd, Dy, Tb)
(2020) Kuznetsov, A. V.; Churkin, O. A.; Popov, V. V.; Shchetinin, I. V.; Ivanov, A. A.; Yaroslavtsev, A. A.; Gaynanov, B. R.; Yastrebtsev, A. A.; Chernysheva, O. V.; Alekseev, P. A.; Menushenkov, A. P.; Кузнецов, Алексей Владимирович; Чуркин, Олег Алексеевич; Попов, Виктор Владимирович; Иванов, Андрей Анатольевич; Гайнанов, Булат Радикович; Ястребцев, Алексей Алексеевич; Чернышева, Ольга Викторовна; Алексеев, Павел Александрович; Менушенков, Алексей Павлович
We present the study of frustrated magnets R2M2O7, where R = Gd, Dy, Tb and M = Ti, Zr. Magnetic susceptibility chi and low-temperature magnetization of perfectly ordered pyrochlores R2Ti2O7, partially disordered fluorites R2Zr2O7, and their completely disordered amorphous phases were measured and analyzed. We have found that structural disorder weakens the exchange interaction of the rare-earth ions. Magnetic moments of dysprosium and terbium, obtained from nearly saturated magnetization, are slightly affected by the disorder while the gadolinium moment is completely independent of it. The local structure of the compounds, including oxygen environment of the rare-earth ions, is discussed in terms of the influence of the crystal electric field on the magnetic properties of R2M2O7.
Только метаданные
Local Disorder in Ln2Ti2O7 (Ln = Gd, Tb, Dy) Pyrochlores
(2019) d'Acapito, F.; Puri, A.; Menushenkov, A. P.; Popov, V. V.; Gaynanov, B. R.; Ivanov, A. A.; Kuznetsov, A. V.; Yaroslavtsev, A. A.; Менушенков, Алексей Павлович; Попов, Виктор Владимирович; Гайнанов, Булат Радикович; Иванов, Андрей Анатольевич; Кузнецов, Алексей Владимирович
© 2019, Pleiades Publishing, Inc.The temperature dependences of extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectra of Ln2Ti2O7 (Ln = Gd, Tb, Dy) geometrically frustrated magnets with a pyrochlore structure are presented. The temperature dependences of the Ln-O and Ti-O interatomic bond lengths and Debye-Waller factors σ2 characterizing the local static and dynamic disordering of bonds have been obtained in the temperature range of 10–300 K. The stiffnesses of metal-oxygen bonds and the parameters of local disordering of the structure have been determined from the dependences σ2(T). The effect of the magnetic state of rare-earth ions on local features of the Ln2Ti2O7 structure has been described. The characteristics of local disorder in pyrochlores under study have been compared to dysprosium zirconate Dy2Zr2O7 having a disordered fluorite structure.
Только метаданные
Magnetic Properties of Eu 0.9 Yb 0.1 B 6
(2019) Anisimov, M. A.; Bogach, A. V.; Azarevich, A. N.; Samarin, N. A.; Kuznetsov, A. V.; Кузнецов, Алексей Владимирович
© 2019, Pleiades Publishing, Ltd. Abstract: The magnetic properties of substitutional solid solutions Eu 0.9 Yb 0.1 B 6 have been investigated in the temperature range of 2–300 K in fields up to 5 T. The data obtained confirm that the state with the electronic and magnetic phase separation (typical of europium hexaboride) is implemented in Eu 0.9 Yb 0.1 B 6 when the system metallization (T M ≈ 15 K) precedes the ferromagnetic ordering (T C ≈ 11.4 K). An analysis of the curves M(H) in the Belov–Arrott coordinates makes it possible to evaluate spontaneous magnetization M sp and zero field susceptibility χ 0 and determine the character of their critical behavior near the Curie point. The calculated critical indices (γ ≈ 1.28 and β ≈ 0.34) are in agreement with the predictions of the three-dimensional Heisenberg model.
Только метаданные
Inhomogeneous superconductivity in LuxZr1-x B12 dodecaborides with dynamic charge stripes
(2021) Azarevich, A.; Bogach, A.; Glushkov, V.; Demishev, S.; Kuznetsov, A.; Кузнецов, Алексей Владимирович
© 2021 American Physical Society.We have studied the normal and superconductive state characteristics (resistivity, Hall coefficient, heat capacity, and magnetization) of model strongly correlated electronic systems LuxZr1-xB12 with cooperative Jahn-Teller instability of the boron rigid cage and with dynamic charge stripes. It was found that these metals are s-wave dirty limit superconductors with a small mean free path of charge carriers l=5-140Å and with a Cooper pair size changing nonmonotonously in the range 450-4000 Å. The parent ZrB12 and LuB12 borides are type-I superconductors, and Zr to Lu substitution induces a type-I to type-II phase transition providing a variation of the Ginzburg-Landau-Maki parameter in the limits 0.65≤κ1,2≤6. We argue in favor of the two-band scenario of superconductivity in LuxZr1-xB12 with gap values Δ1∼14K and Δ2∼6-8K, with pairing corresponding to strong coupling limit (λe-ph∼1) in the upper band, and to weak coupling (λe-ph∼0.1-0.4) in the lower one. A pseudogap Δps-gap∼60-110K is observed in LuxZr1-xB12 above Tc. We discuss also the possibility of anisotropic single-band superconductivity with stripe-induced both pair breaking and anisotropy, and analyze the origin of a unique enhanced surface superconductivity detected in these model compounds.
Только метаданные
Reversible Valence Transition Eu-3+ ? Eu-2+ ? Eu-3+ in EuxEux Ox (2)+ (3)+ (M = Ti, Zr, Hf) 1-MO3+x /2 : An Analysis of XAFS and XRD Data
(2022) Menushenkov, A. P.; Popov, V. V.; Kuznetsov, A. V.; Molokova, A. Y.; Yastrebtsev, A. A.; Gaynanov, B. R.; Rudakov, S. G.; Менушенков, Алексей Павлович; Попов, Виктор Владимирович; Кузнецов, Алексей Владимирович; Ястребцев, Алексей Алексеевич; Гайнанов, Булат Радикович; Рудаков, Сергей Геннадьевич
The regularities of completely reversible valence transition Eu3+. Eu2+. Eu3+ in complex europium oxides have been investigated using a combination of X-ray diffraction (XRD) and X-ray absorption spectroscopy (XANES + EXAFS) synchrotron methods. The influence of the type of M4+ cations on the reduction and oxidation, as well as the formation and evolution of the crystalline and local structure of the (M = Ti, Zr, Hf) compounds is established. It is shown that oxidation of initially reduced Eu2+MO3 samples leads to the formation of mixed-valence (MV) state Eu2+/Eu3+ with inhomogeneous charge distribution, causing a phase transition with formation of partially amophized intermediate metastable phases Eu3+MO3.5 having a monoclinic structure (sp. gr..1211). An increase in the oxidative annealing temperature to 1000 degrees. facilitates further phase transition with the formation of stable cubic phases Eu M2O7.
Только метаданные
Magnetic Response of Conduction Electrons in Nonmagnetic YB6, LaB6, and YbB6 Hexaborides with Electronic and Structural Instabilities
(2023) Sluchanko, N. E.; Kuznetsov, A. V.; Azarevich, A. N.; Bogach, A. V.; Кузнецов, Алексей Владимирович
Только метаданные
Localized Superconductivity in LaB6 Hexaboride with Dynamic Charge Stripes
(2024) Azarevich, A. N.; Bogach, A. V.; Khrykina, O. N.; Bolotina, N. B.; Kuznetsov, A. V.; Кузнецов, Алексей Владимирович
Только метаданные
Direct evidence of real-space pairing in BaBiO3
(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