Персона: Прищепа, Сергей Леонидович
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Институт нанотехнологий в электронике, спинтронике и фотонике
Институт ИНТЭЛ занимается научной деятельностью и подготовкой специалистов в области исследования физических принципов, проектирования и разработки технологий создания компонентной базы электроники гражданского и специального назначения, а также построения современных приборов на её основе.
Наша основная цель – это создание и развитие научно-образовательного центра мирового уровня в области наноструктурных материалов и устройств электроники, спинтроники, фотоники, а также создание эффективной инновационной среды в области СВЧ-электронной и радиационно-стойкой компонентной базы, источников ТГц излучения, ионно-кластерных технологий материалов.
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Прищепа
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Сергей Леонидович
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15 results
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- ПубликацияТолько метаданныеAnisotropy of Assemblies of Densely Packed Co-Alloy Nanoparticles Embedded in Carbon Nanotubes(2019) Prischepa, S. L.; Danilyuk, A. L.; Kukharev, A. V.; Cojocaru, C. S.; Kargin, N. I.; Прищепа, Сергей Леонидович; Каргин, Николай ИвановичIEEEWe report on the magnetic properties of an array of binary metal CoFe, CoNi and CoPt nanoparticles (NPs) embedded inside vertically-oriented carbon nanotubes (CNTs). Samples were synthesized by chemical vapor deposition activated by current discharge plasma and hot filaments. Assemblies of Co-based catalytic NPs have been preliminary formed on SiO2/Si substrates by sputtering of ultrathin films followed by reduction in a H2/NH3 mixture. As a result of the CNT growth, each CNT contained only one ferromagnet top-located NP. For all samples the easy axis of magnetization was oriented along the CNT axis. Using the obtained experimental data and the random anisotropy model, the magnetic parameters like the effective anisotropy constant, the contribution of dipole interaction, shape, magnetocrystalline and magnetoelastic anisotropy were estimated. It is shown that the latter contribution of anisotropy is decisive. From the obtained magnetoelasticity the stresses in NPs embedded inside CNTs were determined. Finally, the magnetization distribution in CoFe, CoNi and CoPt NPs was simulated considering the magnetoelastic contribution.
- ПубликацияТолько метаданныеAnisotropic Temperature-Dependent Interaction of Ferromagnetic Nanoparticles Embedded Inside CNT(2019) Danilyuk, A.; Prischepa, S.; Прищепа, Сергей ЛеонидовичWe analyze the magnetization versus magnetic field curves of Fe-based nanoparticles embedded inside CNT. Measurements were performed at different temperatures and orientations of the magnetic field. We demonstrate that, for the parallel field the magnetic anisotropy dominates and the coherent anisotropy is of great importance at low temperatures. At high temperatures, the exchange coupling becomes stronger, but the coherent anisotropy still occurs. For the perpendicular field, the coherence anisotropy is absent, and the dimensionality of the system reduces to 2D. The results are discussed in the framework of the correlation functions of the magnetic anisotropy axes.
- ПубликацияТолько метаданныеMagnetic Relaxation Experiments in CNT-Based Magnetic Nanocomposite(2019) Calvo-de, la, Rosa, J.; Danilyuk, A. L.; Tejada, J.; Komissarov, I. V.; Prischepa, S. L.; Прищепа, Сергей Леонидович© 2019, Springer Science+Business Media, LLC, part of Springer Nature. In this work, we discuss the relaxation of the magnetic moments in a novel carbon nanotube (CNT)-based nanocomposite synthesized by using chemical vapor deposition process. The material consists of a matrix of CNT filled by Fe-based nanoparticles. This structure is seen clearly by scanning and transmission. X-ray diffraction and Raman spectroscopy are used to detect the predominant Fe 3 C phase and the CNT presence in the sample, respectively. The results obtained from both hysteresis cycles, M(H), and zero field cooled-field cooled (ZFC-FC) measurements confirm that the material is characterized by both a strong ferromagnetic exchange and random magnetic anisotropy. For the first time, we have been able to fit the magnetic relaxation data, M(t), by using both the two distributions of nanoparticles data deduced from the ZFC-FC data and the temperature dependence of the magnetic anisotropy obtained from the law of approach to saturation in random magnets. [Figure not available: see fulltext.].
- ПубликацияТолько метаданныеAnisotropy of Assemblies of Densely Packed Co-Alloy Nanoparticles Embedded in Carbon Nanotubes(2019) Danilyuk, Alexander L.; Kukharev, Andrei V.; Cojocaru, Costel S.; LeNormand, Francois; Prischepa, Serghej L.; Kargin, Nikolai I.; Прищепа, Сергей Леонидович; Каргин, Николай ИвановичWe report on the magnetic properties of an array of binary metal CoFe, CoNi, and CoPt nanoparticles (NPs) embedded inside vertically oriented carbon nanotubes (CNTs). Samples were synthesized by chemical vapor deposition activated by current discharge plasma and hot filaments. Assemblies of Co-based catalytic NPs were prepared on SiO2/Si substrates by sputtering ultrathin films followed by reduction in an H-2/NH3 mixture. As a result of the CNT growth, each CNT contained only one ferromagnetic NP located at the top. For all samples, the easy axis of magnetization was along the CNT axis. The magnetic parameters, including effective anisotropy constant and the contributions of dipole interactions and shape, magnetocrystalline, and magnetoelastic anisotropies, were estimated based on the experimental data and a random-anisotropy model. The magnetoelastic contribution was decisive. From the magnetoelasticity, the stresses in the NPs embedded in the CNTs were determined. Finally, the magnetization distribution in CoFe, CoNi, and CoPt NPs was simulated considering the magnetoelastic contribution.
- ПубликацияТолько метаданныеFemtosecond light pulse response of photodetectors based on Graphene/n-Si heterojunctions(2019) Scagliotti, M.; Salvato, M.; De, Crescenzi, M.; Kovalchuk, N. G.; Komissarov, I. V.; Prischepa, S. L.; Прищепа, Сергей Леонидович© 2019 Elsevier LtdTo take advantage of the graphene appealing electronic properties, in this work we present a photodetector (PD) based on graphene/n-silicon heterojunction (GSH). In this device, graphene acts as light transmitter, counter electrode junction element and photocarrier collector. The photodetector has been provided with metal contacts allowing either photovoltaic or photoconductive operation mode. We investigated the response of GSH PD to a 35-femtosecond laser pulse. In the photovoltaic configuration, the PD exhibits rise times of some tens of nanoseconds, detecting light from ultraviolet (275 nm) to infrared (1150 nm). In photoconductive mode applying a gate voltage VG, the external quantum efficiency hugely increases, from a value of 2% up to 200%. Together with the observation of a rise time, that decreases down to a minimum value of about 1 ns, this makes our device even more competitive and comparable with commercial photodetectors.
- ПубликацияТолько метаданныеLong-Range Exchange Interaction Between Ferromagnetic Nanoparticles Embedded in Carbon Nanotubes(2022) Danilyuk, A. L.; Kukharev, A. V.; Prischepa, S. L.; Прищепа, Сергей ЛеонидовичIEEEIndirect exchange coupling mediated by the conduction electrons (Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange) is studied in the multiwall carbon nanotubes (MWCNTs) of diameters of tens of nanometers with single domain ferromagnetic nanoparticles (FNPs) embedded inside. By adapting the Klinovaja-Loss (KL) model [Phys. Rev. B 87, 045422 (2013)] for single wall CNT and applying the parameters of MWCNTs, we show that the static spin susceptibility can propagate up to tens of micrometers. The main condition for the long-range exchange interaction is the adjustment of the Fermi level to the gap opened by the SOI. At typical diameters of the inner shell of MWCNTS of 20-30 nm the required shift of the Fermi level is much smaller than for single wall CNT and does not exceed tens of meV. The proposed approach allows evaluating the energy of the exchange interaction between FNPs belonging to the same CNT. The obtained results open up good opportunities for the realization and implementation of MWCNT-based spintronic devices.
- ПубликацияТолько метаданныеAnisotropy of assemblies of densely packed ferromagnetic nanoparticles embedded in carbon nanotubes(2020) Danilyuk, A. L.; Prischepa, S. L.; Komissarov, I. V.; Прищепа, Сергей Леонидович© 2020 Nova Science Publishers, Inc. All rights reserved.We report the results related to the impact of magnetic anisotropy on the properties of a new type of nanocomposite consisting of ferromagnetic nanoparticles (NP) embedded in carbon nanotubes (CNT). Samples were synthesized by chemical vapor deposition. We found that for low NP concentration, NPs are intercalated mainly inside CNTs and the extended magnetic order, up to hundreds of nanometers, presents in samples. It is shown by analyzing the correlation functions of the magnetic anisotropy axes that the extended order is not simply due to random anisotropy but is associated with the coherent magnetic anisotropy. With increasing temperature, the extended magnetic order is lost, the exchange coupling becomes stronger, but the coherent anisotropy still occurs. The magnetic coupling between NPs distant from each other for tens and hundreds of nanometers could occur via the RKKY interaction. The magnetic relaxation measurements confirmed the importance of the magnetic anisotropy at low temperatures. For the first time, we have been able to analyze the relaxation data using the temperature dependence of the magnetic anisotropy. We demonstrate further that, when each nanotube contains only one ferromagnetic NP, the magnetoelastic anisotropy plays an important role and leads to the formation of densely packed array of magnetically isolated nanoparticles.
- ПубликацияТолько метаданныеRaman Spectroscopy Study of the Charge Carrier Concentration and Mechanical Stresses in Graphene Transferred Employing Different Frames(2023) Dronina, E. A.; Mikhalik, M. M.; Kovalchuk, N. G.; Niherysh, K. A.; Prischepa, S. L.; Прищепа, Сергей Леонидович
- ПубликацияТолько метаданныеCorrelation analysis of vibration modes in physical vapour deposited Bi2Se3 thin films probed by the Raman mapping technique(2021) Niherysh, K. A.; Andzane, J.; Mikhalik, M. M.; Zavadsky, S. M.; Dobrokhotov, P. L.; Prischepa, S. L.; Komissarov, I. V.; Прищепа, Сергей ЛеонидовичIn this work, the Raman spectroscopy mapping technique is used for the analysis of mechanical strain in Bi2Se3 thin films of various (3-400 nm) thicknesses synthesized by physical vapour deposition on amorphous quartz and single-layer graphene substrates. The evaluation of strain effects is based on the correlation analysis of in-plane (E2g) and out-of-plane (A21g) Raman mode positions. For Bi2Se3 films deposited on quartz, experimental datapoints are scattered along the line with a slope of similar to 0.85, related to the distribution of hydrostatic strain. In contrast to quartz/Bi2Se3 samples, for graphene/Bi2Se3 heterostructures with the same thicknesses, an additional negative slope of similar to-0.85, which can be associated with the distribution of the in-plane (a-b) biaxial tensile strain due to the film-substrate lattice mismatch, is observed. The algorithm of phonon deformation potential (PDP) calculation based on the proposed strain analysis for the 3 nm thick Bi2Se3 film deposited on the graphene substrate, where the strain is considered to be coherent across the thickness, is demonstrated. The PDPs for biaxial in-plane strain of the Bi2Se3 3 nm film in in-plane and out-of-plane modes are equal to -7.64 cm(-1)/% and -6.97 cm(-1)/%, respectively.
- ПубликацияТолько метаданныеSuperconducting critical temperature and softening of the phonon spectrum in ultrathin Nb and NbN/graphene hybrids(2021) Prischepa, S. L.; Kushnir, V. N.; Cirillo, C.; Granata, V.; Komissarov, I.; Прищепа, Сергей ЛеонидовичSuperconductivity is studied in hybrids consisting of ultrathin superconducting film/few layer graphene. Two different superconductors are used for this purpose, Nb and NbN. An increase in the superconducting critical temperature T (c) is observed when graphene is put into contact with Nb. The largest increase is obtained for the thinnest Nb layer, which has a T (c) 8% larger with respect to the single Nb film. In the case of NbN the effect is not as pronounced. Experimental data are discussed by considering the possible modification of the phonon spectrum in the superconductor due to the presence of the graphene. Within an elementary one-dimensional model based on elastic coupling between nearest-neighbor atoms, we demonstrate that the phonon spectrum in the superconductor is modified at low energies with the subsequent enhancement of the effective electron-phonon coupling constant. While the strong oscillating nature of the electron-phonon interaction, alpha (2)(omega), in NbN could lead to the insensitivity of T (c) on the low-energy phonons generated by the graphene, the almost constant behavior of alpha (2)(omega) in Nb favors the increase of the superconducting critical temperature.