38 results on '"M. N. Sarychev"'
Search Results
2. Adiabatic Potential Energy Surface of Jahn–Teller Cu2+$${\text{F}}_{8}^{ - }$$ Complexes in a Fluorite Crystal
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M. N. Sarychev, W. A. L. Hosseny, I. V. Zhevstovskikh, V. A. Ulanov, A. V. Egranov, V. T. Surikov, N. S. Averkiev, and V. V. Gudkov
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General Physics and Astronomy - Published
- 2022
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3. Relaxation Contribution of a System of Jahn–Teller Complexes to the Elastic Moduli of Doped Fluorites
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V. T. Surikov, V. V. Gudkov, A. S. Bondarevskaya, M. N. Sarychev, I. V. Zhevstovskikh, N. S. Averkiev, V. A. Ulanov, A. V. Egranov, and G. S. Shakurov
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Tetragonal crystal system ,Materials science ,Condensed matter physics ,law ,Jahn–Teller effect ,Relaxation (NMR) ,Potential energy surface ,General Physics and Astronomy ,Ground state ,Electron paramagnetic resonance ,Potential energy ,Ion ,law.invention - Abstract
The results of the study of the temperature dependence of attenuation and velocity of ultrasonic waves are presented for CaF2:Cr and CaF2:Ni crystals in which Cr2+ and Ni2+ ions substitute calcium ions, forming Jahn–Teller (JT) complexes [CrF8]6– and [NiF8]6–. The Cr2+ and Ni2+ ions in the fluorite structure have threefold orbital degeneracy in the ground state, are described by the T $$ \otimes $$ (e + t2) Jahn–Teller effect (JTE) problem, and have an adiabatic potential energy surface (APES) defined in the five-dimensional space of trigonal and tetragonal symmetrized coordinates whose lower sheet is a simply connected surface with orthorhombic minima separated by potential energy barriers. The temperature dependence of the ultrasonic attenuation and velocity exhibits anomalies typical of the relaxation contributions of systems of JT complexes in the low-temperature region. The effect of tunneling relaxation mechanisms (direct and two-phonon transitions) on the JT contribution to the complex elastic moduli and to the error in determining the relaxation time is analyzed. Based on the approach that takes into account both tunneling and activation mechanisms of relaxation, the activation energies and the constants characterizing these relaxation mechanisms are determined in CaF2:Cr2+ and CaF2:Ni2+ crystals.
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- 2021
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4. Tunneling Relaxation Mechanisms of the Jahn–Teller Complexes in a CaF2:Cr2+ Crystal
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M. N. Sarychev, A. V. Egranov, A. S. Bondarevskaya, I. V. Zhevstovskikh, N. S. Averkiev, G. S. Shakurov, V. T. Surikov, V. A. Ulanov, and V. V. Gudkov
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Materials science ,Physics and Astronomy (miscellaneous) ,Solid-state physics ,Jahn–Teller effect ,Atmospheric temperature range ,01 natural sciences ,Potential energy ,Molecular physics ,010305 fluids & plasmas ,Ion ,Crystal ,0103 physical sciences ,Potential energy surface ,Relaxation (physics) ,010306 general physics - Abstract
The temperature dependences of attenuation and the velocity of ultrasonic waves at frequencies of 26–158 MHz in a CaF2 fluorite crystal at the substitution of Jahn–Teller Cr2+ centers for calcium ions have been studied. An abnormally high relaxation rate, which is two orders of magnitude higher than the relaxation rate in other previously studied CaF2:Ni2+ and SrF2:Cr2+ fluorites, has been found in the system of Jahn–Teller complexes in the low-temperature region. It has been shown that the global minima of the adiabatic potential energy surface of the Cr2+ $${\text{F}}_{8}^{ - }$$ complexes in the CaF2:Cr2+ crystal also have orthorhombic symmetry but are separated by significantly lower potential energy barriers than in CaF2:Ni2+ and SrF2:Cr2+ crystals. It has been found that tunneling relaxation mechanisms (direct and two-phonon transitions) are dominant, rather than thermal activation, in CaF2:Cr2+ in the temperature range where the Jahn–Teller effect is manifested in an ultrasonic experiment. The parameters characterizing these relaxation mechanisms have been determined.
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- 2021
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5. Jahn–Teller Cr2+ Centers in a CdSe Crystal
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I. V. Zhevstovskikh, Yu. V. Korostelin, M. N. Sarychev, V. V. Gudkov, and G. S. Shakurov
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010302 applied physics ,Materials science ,Solid-state physics ,Jahn–Teller effect ,Condensed Matter Physics ,01 natural sciences ,Molecular physics ,Spectral line ,Electronic, Optical and Magnetic Materials ,Ion ,law.invention ,Crystal ,Tetragonal crystal system ,Impurity ,law ,Condensed Matter::Superconductivity ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,Electron paramagnetic resonance - Abstract
Impurity Cr2+ ions in the CdSe crystal are studied by tunable EPR spectroscopy in the frequency range of 70–320 GHz. The discovered Jahn–Teller tetragonal distortions of the nearest environment of the chromium ion confirm the results of recent ultrasound studies. The set of spectroscopic parameters that allows obtaining agreement between the calculates and experimental angular and field–frequency dependences of the EPR spectra is determined.
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- 2020
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6. Sub-lattice of Jahn-Teller centers in hexaferrite crystal
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Martin Dressel, V. V. Gudkov, Sergei Zherlitsyn, I. V. Zhevstovskikh, M. N. Sarychev, S.A. Gudkova, N. S. Averkiev, Rainer Niewa, L. N. Alyabyeva, Isaac B. Bersuker, Boris Gorshunov, and Denis Vinnik
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0301 basic medicine ,Ferroelectrics and multiferroics ,Materials science ,Quantum dynamics ,Jahn–Teller effect ,lcsh:Medicine ,02 engineering and technology ,Article ,Ion ,03 medical and health sciences ,Lattice (order) ,lcsh:Science ,Terahertz optics ,Multidisciplinary ,Doping ,lcsh:R ,Acoustics ,021001 nanoscience & nanotechnology ,Potential energy ,Magnetic field ,Crystallography ,030104 developmental biology ,Condensed Matter::Strongly Correlated Electrons ,lcsh:Q ,0210 nano-technology ,Ground state - Abstract
A novel type of sub-lattice of the Jahn-Teller (JT) centers was arranged in Ti-doped barium hexaferrite BaFe12O19. In the un-doped crystal all iron ions, sitting in five different crystallographic positions, are Fe3+ in the high-spin configuration (S = 5/2) and have a non-degenerate ground state. We show that the electron-donor Ti substitution converts the ions to Fe2+ predominantly in tetrahedral coordination, resulting in doubly-degenerate states subject to the E⊗ e problem of the JT effect. The arranged JT complexes, Fe2+O4, their adiabatic potential energy, non-linear and quantum dynamics, have been studied by means of ultrasound and terahertz-infrared spectroscopies. The JT complexes are sensitive to external stress and applied magnetic field. For that reason, the properties of the doped crystal can be controlled by the amount and state of the JT complexes. © 2020, The Author(s). Deutscher Akademischer Austauschdienst, DAAD Russian Foundation for Basic Research, RFBR: 18–02–00332 a Deutscher Akademischer Austauschdienst, DAAD: 91728513 Ministry of Education and Science of the Russian Federation, Minobrnauka: 19–53–04010 19–72–00055 Ministry of Education and Science of the Russian Federation, Minobrnauka The authors acknowledge fruitful discussions with A.S. Prokhorov. We acknowledge support of the HLD at HZDR, member of the European Magnetic Field Laboratory (EMFL). At Ural Federal University, the research was supported by the Russian Foundation for Basic Research (18–02–00332 a), UrFU Center of Excellence “Radiation and Nuclear Technologies” (Competitiveness Enhancement Program), the Ministry of Education and Science of the Russian Federation (Program 5–100). In M.N. Miheev Institute of Metal Physics, the research was carried out within the state assignment of the Ministry of Education and Science of the Russian Federation (theme “Electron” No. AAAA-A18–118020190098–5. At South Ural State University, the authors were generally supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0011. The single crystal growth part was supported by Russian Foundation for Basic Research (19–53–04010). At Moscow Institute of Physics and Technology, the work was supported by the Russian Ministry of Education and Science (Program 5–100) and by the German Academic Exchange Service (DAAD) Michael Lomonosov Programm Linie B, 91728513. Time-domain low temperature spectroscopic experiments were financially supported by the Russian Scientific Foundation (19–72–00055).
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- 2020
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7. Contribution of the distorted Jahn-Teller complexes to the elastic moduli in fluorite crystal
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M. N. Sarychev, W. A. L. Hosseny, V. A. Ulanov, A. V. Egranov, V. T. Surikov, I. V. Zhevstovskikh, N. S. Averkiev, and V. V. Gudkov
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- 2022
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8. Ultrasonic Determination of the Jahn–Teller Effect Parameters in Impurity-Containing Crystals
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V. V. Gudkov, V. T. Surikov, Yu. V. Korostelin, M. N. Sarychev, N. S. Averkiev, Shadi Yasin, Isaac B. Bersuker, Sergei Zherlitsyn, and I. V. Zhevstovskikh
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Physics ,Solid-state physics ,Jahn–Teller effect ,Degenerate energy levels ,General Physics and Astronomy ,01 natural sciences ,Molecular physics ,Isothermal process ,Crystal ,Impurity ,Normal mode ,Condensed Matter::Superconductivity ,0103 physical sciences ,010306 general physics ,Adiabatic process - Abstract
A method is developed to determine the symmetry properties of strains and the type of Jahn–Teller effect in crystals with impurity ions in a triply degenerate electronic T state. This method is based on a calculation of the isothermal contribution of the impurity subsystem to the elastic moduli of a crystal and the absorption and velocity of normal modes for all three possible problems, namely, T ⊗ e, T ⊗ t2, and T ⊗ (e + t2). The calculation results are compared with experimental data. The efficiency of the method is demonstrated for a CdSe:Cr2+ crystal. The CrSe4 center is found to be described in terms of the problem T ⊗ e. The parameters of the ground-state adiabatic potential are determined.
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- 2019
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9. Determining the Parameters of the Jahn–Teller Effect in Impurity Centers from Ultrasonic Experiments: Application to the ZnSe : Ni2+ Crystal
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V. V. Gudkov, N. S. Averkiev, M. N. Sarychev, Isaac B. Bersuker, I. V. Zhevstovskikh, and V. T. Surikov
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010302 applied physics ,Materials science ,Jahn–Teller effect ,Relaxation (NMR) ,Condensed Matter Physics ,01 natural sciences ,Potential energy ,Molecular physics ,Electronic, Optical and Magnetic Materials ,Crystal ,Tetragonal crystal system ,Normal mode ,Impurity ,0103 physical sciences ,Potential energy surface ,010306 general physics - Abstract
The earlier developed methodology of ultrasonic investigation for determining the parameters of the Jahn–Teller effect (JTE) in impurity centers in crystals is further developed in application to Ni2+ impurities in ZnSe : Ni2+. For all normal modes propagating along the [110] axis, the temperature dependences of the attenuation of ultrasound are measured in the frequency range 25–165 MHz. At a temperature of about 13 K, for all these modes, attenuation peaks are observed, which indicate the presence of local distortions of both trigonal and tetragonal types. Following the previously developed method, it is shown that these anomalies of attenuation are caused by the relaxation transitions between equivalent local distortions induced by the JTE at the Ni2+ centers. In the tetrahedral environment of selenium, this ion is in the threefold degenerate ground electron state 3T1, in which three types of the JTE can be realized. The data of ultrasonic experiments indicate the realization of the T ⊗ (e + t2) problem, in which the potential energy surface has four equivalent minima of the trigonal type, slightly deformed toward tetragonal saddle points. The trigonal vibronic constants, the stabilization energies of the trigonal minima, and the activation energy of the barriers between them are ev-aluated.
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- 2019
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10. Effects of irradiation of ZnO/CdS/Cu2ZnSnSe4/Mo/glass solar cells by 10 MeV electrons on photoluminescence spectra
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M. A. Sulimov, J. Márquez-Prieto, Robert W. Martin, Paul R. Edwards, A. V. Mudryi, V. Yu. Ivanov, Ian Forbes, M. N. Sarychev, Jüri Krustok, and M. V. Yakushev
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Free electron model ,CADMIUM SULFIDE ,Materials science ,Photoluminescence ,ZINC OXIDE ,POTENTIAL FLUCTUATIONS ,02 engineering and technology ,Electron ,RED SHIFT ,01 natural sciences ,Molecular physics ,Spectral line ,0103 physical sciences ,CARRIER MOBILITY ,TEMPERATURE DEPENDENCIES ,General Materials Science ,Irradiation ,TEMPERATURE ,QC ,BUFFER LAYERS ,010302 applied physics ,Mechanical Engineering ,PHOTOLUMINESCENCE SPECTRUM ,VARIABLE TEMPERATURE ,SOLAR CELLS ,MOLYBDENUM ,DEFECTS ,Liquid nitrogen ,DOPPLER EFFECT ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,II-VI SEMICONDUCTORS ,OXIDE MINERALS ,ELECTRONS ,IRRADIATION ,HIGH ENERGY BANDS ,SECONDARY DEFECT ,Mechanics of Materials ,RADIATION ,Charge carrier ,PHOTOLUMINESCENCE ,0210 nano-technology ,EXCITATION INTENSITY ,RANDOMLY DISTRIBUTED ,Excitation ,LIQUEFIED GASES - Abstract
Solar cells with the structure ZnO/CdS/Cu2ZnSnSe4/Mo/glass were studied by photoluminescence (PL) before and after irradiation with a dose of 1.8 × 1015 cm−2 and then 5.4 × 1015 cm−2 of 10 MeV electrons carried out at 77 K in liquid nitrogen bath. The low temperature PL spectra before irradiation revealed two bands, a broad and asymmetrical dominant band at 0.94 eV from the CZTSe layer and a lower intensity high energy band (HEB) at 1.3 eV, generated by defects in the CdS buffer layer. Analysis of the excitation intensity and temperature dependencies suggested that the dominant band is free-to-bound (FB): the recombination of free electrons with holes localised at acceptors whose energy levels are affected by potential fluctuations of the valence band due to high concentrations of randomly distributed charged defects. Irradiation did not induce any new band in the examined spectral range (from 0.5 μm to 1.65 μm) but reduced the intensity of both bands in the PL spectra measured at 77 K without warming the cells. The higher the dose the greater was the reduction. After this the cells were warmed to 300 K and moved to a variable temperature cryostat to measure temperature dependencies of the PL spectra. After irradiation the red shift rate of the FB band with temperature rise was found to increase. Electrons displace atoms in the lattice creating primary defects: interstitials and vacancies. These defects recombine during and shortly after irradiation forming secondary defect complexes which work as deep non-radiative traps of charge carriers reducing the PL intensity and increasing the rate of the temperature red shift. Irradiation did not affect the mean depth of the band tails estimated from the shape of the low energy side of the dominant PL band. © 2020 Elsevier Ltd European Commission, EC European Regional Development Fund, FEDER: TK141 Ministry of Science and Higher Education of the Russian Federation: АААА-А18-118020290104-2 The research was supported by the Ministry of Science and Higher Education of the Russian Federation (topic “Spin” № АААА-А18-118020290104-2 ) and the European Union through the European Regional Development Fund, Project TK141 .
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- 2020
11. Correlation of elastic and optoelectronic properties near structural phase transition in organic-inorganic lead iodide perovskite single crystals
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Oleg E. Tereshchenko, I. V. Zhevstovskikh, M. N. Sarychev, Olga I Semenova, N. S. Averkiev, and V. A. Golyashov
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Photocurrent ,Phase transition ,Photoluminescence ,Materials science ,business.industry ,Exciton ,02 engineering and technology ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Phase (matter) ,0103 physical sciences ,Optoelectronics ,General Materials Science ,010306 general physics ,0210 nano-technology ,business ,Elastic modulus ,Perovskite (structure) - Abstract
The experimental evidence of the influence of the structural phase transition on the elastic and optoelectronic properties of CH3NH3PbI3 single crystals has been reported. A peak in the attenuation for longitudinal and shear ultrasonic waves and a step-like anomaly in their velocity have been found near the structural the orthorhombic-to-tetragonal phase transition (160 K). The narrow hysteresis observed in the temperature dependences of the elastic properties confirms that this is the first-order phase transition. A redshift of the absorption threshold (of about 110 meV) has been revealed both in the photocurrent (PC) and in the photoluminescence (PL) spectra with increasing temperature from 140 to 160 K. In the orthorhombic phase of CH3NH3PbI3 single crystals, the fine exciton structure in the PC spectrum has been found with an exciton binding energy of 19–25 meV. The peculiarities of the PC and PL spectra near the phase transition temperature (160 K) have been observed within a wider temperature range in contrast to the elastic anomalies that can be explained by the complex structure of the near-surface region. It may be essential for the further development of optoelectronic devices based on hybrid halide perovskites.
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- 2020
12. Radiation-Induced Effects in Ce3+- and Eu2+-Doped Al5O6N
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A. S. Lysenkov, M. N. Sarychev, B. V. Shul’gin, Yu. F. Kargin, A. V. Ishchenko, N. S. Akhmadullina, G. F. Babailova, and V. V. Yagodin
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010302 applied physics ,Materials science ,General Chemical Engineering ,Doping ,Metals and Alloys ,Analytical chemistry ,02 engineering and technology ,Nitride ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,01 natural sciences ,Thermoluminescence ,Ion ,Inorganic Chemistry ,0103 physical sciences ,Materials Chemistry ,Crystallite ,0210 nano-technology ,Luminescence ,Sol-gel - Abstract
Polycrystalline Al5O6N samples have been prepared by sol–gel synthesis followed by carbothermal reduction and nitridation. X-ray luminescence (XRL) spectra and thermoluminescence (TL) curves of Ce3+- and Eu2+-doped aluminum oxynitride have been measured in the temperature range 5–380 K and analyzed. Working TL peaks have been detected in the range 150–250 K for the Al5O6N:Ce3+ sample and in the range 140–200 K for the Al5O6N:Eu2+ samples. There are also lower temperature peaks: in the ranges 10–60 and 20–100 K. The XRL spectra of the samples have been measured at temperatures of 8 (for the first time) and 300 K.
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- 2018
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13. Low-temperature luminescence in organic-inorganic lead iodide perovskite single crystals
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Olga I Semenova, I. V. Zhevstovskikh, M. N. Sarychev, Oleg E. Tereshchenko, and N. S. Averkiev
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chemistry.chemical_classification ,Materials science ,Acoustics and Ultrasonics ,chemistry ,Organic inorganic ,Inorganic chemistry ,Iodide ,Condensed Matter Physics ,Luminescence ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Perovskite (structure) - Abstract
We present a temperature and laser-power dependent photoluminescence (PL) study of methylammonium lead iodide (CH3NH3PbI3) single crystals in the orthorhombic phase. At temperatures below 140 K, we revealed the multi-component PL emission. In addition to a free exciton with an energy of 1.65 eV, we found emission bands with peaks approximately equal to 1.6 eV, 1.52 eV, and 1.48 eV. Analysis of the thermal evolution of the intensities, peak positions, and linewidths of all the PL bands allowed one to determine their origin. We attributed the PL peak with energy of 1.6 eV to a bound exciton, while the free exciton-bound exciton splitting energy is 50–60 meV. The PL emission with an energy of 1.52 eV can be explained by the donor-acceptor pair (DAP) recombination, where donor and acceptor defects have a depth of about 12 meV and 120 meV, respectively. MA (CH3NH3) interstitials (MA i + ) and lead vacancies (V P b 2 − ) are the most suitable for the DAP transition to occur in CH3NH3PbI3 crystals. The 1.48 eV PL emission is consistent with the recombination of self-trapped excitons, and interstitial iodine is likely to be an active trap source. We found the variation of the self-trapped depth from 15 meV (at T < 80 K) to 53 meV (at T > 80 K) with increasing the temperature. Although the multi-component PL emission in CH3NH3PbI3 single crystals appears at low temperatures, defects and excitonic traps that cause this emission can affect the photophysics of hybrid perovskites at higher temperatures.
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- 2021
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14. ADIABATIC POTENTIAL ENERGY SURFACE OF THE JAHN-TELLER COMPLEXES IN SrF2:Cr2+ CRYSTAL
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A. S. Bondarevskaya, N. S. Averkiev, I. V. Zhevstovskikh, M. N. Sarychev, V. A. Ulanov, W. A. L. Hosseny, V. T. Surikov, G. S. Shakurov, and V. V. Gudkov
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Materials science ,Jahn–Teller effect ,Relaxation (NMR) ,Activation energy ,Potential energy ,Molecular physics ,Tetragonal crystal system ,symbols.namesake ,Condensed Matter::Superconductivity ,Potential energy surface ,symbols ,Condensed Matter::Strongly Correlated Electrons ,Adiabatic process ,Hamiltonian (quantum mechanics) - Abstract
Temperature dependence of attenuation of ultrasonic transverse normal modes, polarized propagating along the [110] crystallographic axis in SrF2 crystal doped with Cr2+ ions was measured at the frequency of 52-162 MHz in the temperature range of 4-180 K. The results indicated the T2g⊗ (ee+t2g)Jahn-Teller effect problem with important impact of quadratic term in the vibronic Hamiltonian. The value of activation energy was derived from the temperature dependence of relaxation time of the sub-system of the Jahn-Teller complexes simulated with account of three mechanisms of relaxation: thermal activation, tunnelling through the potential energy barrier, and two-phonons mechanism similar to Raman scattering. The extrema points of adiabatic potential energy surface: six orthorhombic global minima, three tetragonal and four trigonal saddle points were calculated in 5-dimensional space of symmetrized coordinates. © 2020 American Institute of Physics Inc.. All rights reserved. In Ural Federal University this work was supported by the RFBR (grant 18-02-00332_a), UrFU Center of Excellence “Radiation and Nuclear Technologies” (Competitiveness Enhancement Program), the Ministry of Education and Science of the Russian Federation (Program 5-100). In M.N. Miheev Institute of Metal Physics, this work was carried out within the state assignment of the Ministry of Education and Science of the Russian Federation (theme “Electron” No. AAAA-A18-118020190098-5).
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- 2020
15. Influence of irradiation of Cu(In,Ga)Se2 thin films by 10 MeV electrons on photoluminescence spectra
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I. A. Mogilnikov, M. A. Sulimov, O. M. Borodavchenko, M. N. Sarychev, M. V. Yakushev, A. V. Mudryi, V. Yu. Ivanov, and V. D. Zhivulko
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Free electron model ,Materials science ,Photoluminescence ,Annealing (metallurgy) ,Analytical chemistry ,Irradiation ,Electron ,Thin film ,Liquid nitrogen ,Acceptor - Abstract
Thin films of Cu(In,Ga)Se2 on Mo coated glass substrates were studied by photoluminescence (PL) technique before and after irradiation in liquid nitrogen bath with a dose of 1.8 x 1015 cm−2 of 10 MeV electrons to determine the nature of radiation defects in Cu(In,Ga)Se2. The PL spectra before irradiation contain a broad dominant band at 1 eV, consisting of 3 peaks P1, P2 and P3, and two low intensity bands P4 at 0.86 eV and P5 at 0.77 eV. Because of their strong j-shift the P1, P2 and P3 were assigned to the free-to-bound (FB) recombination of free electrons and holes localised at 3 different acceptors whose energy levels are affected by potential fluctuations of the valence band. The P4 and P5 bands were also assigned to the FB recombinations of free electrons but with deeper acceptors. Irradiation reduced the PL intensity of the dominant 3 bands P1, P2 and P3. We assign such a reduction to the formation of nonradiative defects acting as deep traps. Irradiation did not change the j-shift of the P3 band (12 meV/d) suggesting that the acceptor, associated with P3, was not affected by irradiation. However, irradiation reduced the P2 j-shift from 13.8 meV/d to 4 meV/d demonstrating a significant reduction of the compensation level associated with this acceptor. Warming to the room temperature doubled the intensity of the dominant band probably due to annealing of some radiation induced defects. It increased the P2 j-shift to 10 meV/d demonstrating rising compensation level associated with this acceptor.
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- 2020
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16. Effects of chemical treatment of Cu2ZnSnSe4 thin films on photoluminescence of solar cells ZnO/CdS/Cu2ZnSnSe4/Mo/Glass
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V. Y. Ivanov, A. V. Mudryi, V. D. Zhivulko, O. M. Borodavchenko, I. A. Mogilnikov, Ian Forbes, M. N. Sarychev, M. V. Yakushev, and M. A. Sulimov
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Photoluminescence ,Materials science ,Scanning electron microscope ,Analytical chemistry ,Photoluminescence excitation ,Thin film ,Isotropic etching ,Layer (electronics) ,Deposition (law) ,Chemical bath deposition - Abstract
Thin films of Cu2ZnSnSe4 (CZTSe) were fabricated by the selenisation of metallic precursors sequentially deposited on Mo coated glass substrates. The surface morphology and cross section, studied by a scanning electron microscope (SEM), reveal densely packed grains with sizes in excess of 1 µm and CZTSe film with a thickness of 1.4 µm. The elemental composition of both the precursors and CZTSe films was measured by an energy dispersive X-ray analyser demonstrated a copper deficiency and zinc excess as well as a near stoichiometric content of Se. A set of 4 as deposited CZTSe films was used to produce solar cells with the structure ZnO/CdS/Cu2ZnSnSe4/Mo/glass. These films were coated with CdS buffer layer using a standard chemical bath deposition after chemical etching using KCN or/and ammonia: film E was not etched, film B was etched in KCN for 2 minutes, film C was etched in KCN for 5 minutes and film D was etched in KCN for 30s and then in ammonia for 5 minutes. Solar cells were then completed by DC-magnetron deposition of ZnO/ZnO:Al transparent front contacts. Finally solar cells with areas of 3x3 mm2 were separated by mechanical scribing. The structural properties of the cells and phase content of the CZTSe layer were examined by x-ray diffraction (XRD). Low intensity reflexes of the secondary phases SnSe and SnSe2 were also present. The bandgaps Eg of the CZTSe layers in the cells, measured by photoluminescence excitation (PLE) at 4.2 K, were found to be of 1.05 eV in all the four cells. This cell also showed the highest FF of 41.1% whereas the best Isc of 46.6 mA/cm2, demonstrated by the D cell. The highest conversion efficiency of 6.2% was obtained for the E cell, produced without any etch, and for the D one after 30 s etch in KCN plus 5 minutes in ammonia.
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- 2020
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17. IR Luminescence of α-Al2O3 – δ at 4–300 K
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I. I. Milman, V. S. Voinov, A. I. Surdo, R. M. Abashev, and M. N. Sarychev
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010302 applied physics ,Range (particle radiation) ,Materials science ,Photoluminescence ,Physics and Astronomy (miscellaneous) ,Stoichiometric composition ,chemistry.chemical_element ,Corundum ,02 engineering and technology ,Electron ,engineering.material ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ion ,Crystallography ,chemistry ,0103 physical sciences ,engineering ,0210 nano-technology ,Luminescence ,Helium - Abstract
It is established that simple color centers of the F+ and F type (anion vacancies with one or two electrons, respectively) in anion-deficient corundum (α-Al2O3–δ) crystals can be transformed into complex centers (including divacancy centers of the F2 type) using a special thermo-optical treatment. A fine structure of the photoluminescence bands of complex centers of both the known and unknown natures was recorded in these crystals at helium temperatures in the near-IR range. A comparison with the photoluminescence bands in neutron-irradiated α-Al2O3 samples with the initial stoichiometric composition reveals their complete similarity, which indicates the possibility of nonradiative formation of complex centers in α-Al2O3.
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- 2018
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18. Elastic Moduli in Cadmium Selenide Doped with Chromium
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Yu. V. Korostelin, M. N. Sarychev, V. V. Gudkov, Sergei Zherlitsyn, I. V. Zhevstovskikh, N. S. Averkiev, Sh. Yasin, and Isaac B. Bersuker
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010302 applied physics ,Materials science ,Cadmium selenide ,Condensed matter physics ,Jahn–Teller effect ,Doping ,Relaxation (NMR) ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Moduli ,Crystal ,chemistry.chemical_compound ,Chromium ,chemistry ,0103 physical sciences ,0210 nano-technology ,Elastic modulus - Abstract
Temperature dependence of elastic moduli (C11 − C12 ) / 2 , C33 , and C44, the latter for the piezo-active and non-piezo-active versions, have been measured in the interval of 4 - 180 K at 28 - 262 MHz in a CdSe: Cr2+ crystal. Anomalies below 40 K have been found for all the moduli, except C33 . The interpretation of the results has been carried out involving the Jahn-Teller effect and relaxation between the equivalent distortions of the tetrahedral CrSe4 centers.
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- 2017
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19. Magnetic Field Induced Relaxation Attenuation of Ultrasound by Jahn–Teller Centers: Application to ZnSe:Cr2+
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Shadi Yasin, V. V. Gudkov, Isaac B. Bersuker, Sergei Zherlitsyn, I. V. Zhevstovskikh, M. N. Sarychev, A. M. Monakhov, Yuriy V. Korostelin, N. S. Averkiev, and K. A. Baryshnikov
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010302 applied physics ,Materials science ,Solid-state physics ,Condensed matter physics ,Jahn–Teller effect ,Attenuation ,Relaxation (NMR) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Polarization (waves) ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,law.invention ,Magnetic field ,Crystal ,Nuclear magnetic resonance ,law ,0103 physical sciences ,0210 nano-technology ,Electron paramagnetic resonance - Abstract
The influence of magnetic fields on ultrasonic attenuation caused by relaxation in Jahn–Teller centers is studied using chromium ions as Zn substitute impurities in the ZnSe crystal as an example. The changes of the position and shape of the relaxation peak with the applied magnetic field induction B were observed in the temperature dependence of the ultrasonic attenuation of the shear waves at the frequency of 29.5 MHz propagating along the [110] axis with the polarization vector parallel to the [1 $$\overline{1}$$ 0] axis. To rationalize the results, a simulation procedure was employed assuming that there are two thermal activation mechanism of relaxation with different relaxation times. One of them emerged with activation energy $$V_0=75$$ K that remains unchanged in the magnetic fields, the other occurs with increasing $$V_0$$ up to $$V_0=106$$ K at $$B=14$$ T.
- Published
- 2016
- Full Text
- View/download PDF
20. Adiabatic potential energy surface of the Jahn-Teller complexes in CaF2:Ni2+ crystal determined from experiment on ultrasonic attenuation
- Author
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A. S. Bondarevskaya, V. V. Gudkov, I. V. Zhevstovskikh, M. N. Sarychev, W. A. L. Hosseny, N. S. Averkiev, V. T. Surikov, A.V. Egranov, and O.S. Grunskiy
- Subjects
Physics ,Mechanical Engineering ,Jahn–Teller effect ,Metals and Alloys ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular physics ,0104 chemical sciences ,Crystal ,Tetragonal crystal system ,Vibronic coupling ,Mechanics of Materials ,Saddle point ,Potential energy surface ,Materials Chemistry ,Relaxation (physics) ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology ,Adiabatic process - Abstract
In CaF2 crystal doped with Ni2+ ions, attenuation of all the normal ultrasonic modes with the wave vector k | | ⟨ 110 ⟩ were investigated at 14–161 MHz in the temperature region of 5–120 K. The observed peaks of relaxation origin were interpreted as manifestation of the Jahn-Teller effect subject to the T 1 g ⊗ ( e g + t 2 g ) problem. The experimental data made it possible to estimate the parameters of adiabatic potential energy surface: the Jahn-Teller stabilization energies, the linear and quadratic vibronic coupling constants, location of the saddle points and the global minima defined in the 5-dimensional space of symmetrized (tetragonal and trigonal) coordinates.
- Published
- 2020
- Full Text
- View/download PDF
21. Interplay Between Relaxation and Resonance in Ultrasound Attenuation by the Cubic Crystal ZnSe:Cr
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Sergei Zherlitsyn, N. S. Averkiev, I. V. Zhevstovskikh, M. N. Sarychev, V. V. Gudkov, Isaac B. Bersuker, Yuri V. Korostelin, Shadi Yasin, and K. A. Baryshnikov
- Subjects
Materials science ,Nuclear magnetic resonance ,Jahn–Teller effect ,Ultrasound attenuation ,Resonance ,Relaxation (physics) ,Cubic crystal system ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Abstract
Resonance ultrasound attenuation, albeit broadened, is observed in doped cubic crystal ZnSe with a part of the Zn ions substituted by magnetic anisotropic Cr2+ ions. In the tetrahedral selenium environment the latter form a T term Jahn–Teller (JT) center with a T⊗e JT problem and three equivalent distortions along the three tetragonal axes. In sufficiently strong magnetic fields (B > 4 T) applied along the [001] direction the degeneracy of the ground state is removed, and the ultrasound wave propagating along [110] and polarized along [110] (at T = 1.3 K) does not interact with the center, its impurity attenuation being reduced to zero. By comparison, this allows to estimate the contribution of the Cr centers to the attenuation of ultrasound in the ZnSe:Cr crystal in zero magnetic field. The experimental data revealed a strong dependence of the attenuation on the ultrasound frequency, evidencing for the resonance nature of the attenuation: there is no frequency dependence in relaxational attenuation with the relaxation time much larger than the period of the ultrasonic wave. The resonance attenuation is attributed to transitions between the ground state energy levels, split by spin-orbital interaction. The high sensitivity of the resonance absorption on the ultrasound power is also discussed.
- Published
- 2019
22. Observation of Low-Temperature Softening of Transverse Elastic Modulus Due to Cobalt Impurities in Mercury Selenide
- Author
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V. V. Gudkov, Myroslav D. Andriichuk, V. I. Okulov, Kirill A. Medvedev, I. V. Zhevstovskikh, M. N. Sarychev, and Lidiya D. Paranchich
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010302 applied physics ,Materials science ,Analytical chemistry ,chemistry.chemical_element ,Electron ,Dielectric ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Crystal ,chemistry.chemical_compound ,chemistry ,Impurity ,0103 physical sciences ,General Materials Science ,Mercury selenide ,010306 general physics ,Softening ,Cobalt ,Elastic modulus - Abstract
Influence on elastic moduli of donor electron d-states of cobalt impurities has been investigated in mercury selenide crystals. Experiments have been carried out at the frequency of 53 MHz in the temperature interval of 1.3–100 K. Softening of the $$(C_{11} - C_{12})/2$$ modulus below 10 K has been observed in the impurity crystals in contrast with the $$(C_{11} + C_{12} + 2C_{44})/2$$ and $$C_{44}$$ moduli those have exhibited hardening at cooling typical for dielectric and semiconductor crystals. The softening of the elastic modulus has been interpreted as manifestation of hybridization of the impurity d-states in the conduction band of the crystal. Comparison of theoretical calculations with experimental data has been proved to be in good agreement and has made it possible to determine the parameters characterizing the hybridized electron states.
- Published
- 2015
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23. Temperature anomaly of the coefficient of ultrasonic absorption by electrons of hybridized states of cobalt impurities in mercury selenide
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V. V. Gudkov, M. N. Sarychev, V. Yu. Mayakin, I. V. Zhevstovskikh, V. I. Okulov, L. D. Paranchich, and M. D. Andriichuk
- Subjects
Materials science ,Solid-state physics ,Condensed matter physics ,chemistry.chemical_element ,Transverse wave ,Atmospheric temperature range ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Crystal ,chemistry.chemical_compound ,chemistry ,Impurity ,Condensed Matter::Superconductivity ,Attenuation coefficient ,Mercury selenide ,Cobalt - Abstract
The effects of the interaction of ultrasound with donor d electrons of cobalt impurity atoms at low concentrations in mercury selenide crystals have been investigated. The temperature dependences of the electronic contribution to the absorption coefficient at a frequency of 53 MHz in crystals with cobalt concentrations from 1018 to 1020 cm−3 and in the undoped crystal have been observed experimentally. It has been found that crystals with impurities are characterized by an anomalous nonmonotonic temperature dependence of the absorption coefficient of the slow transverse wave in a narrow temperature range near 10 K. A smooth monotonic temperature dependence has been observed for longitudinal and fast transverse waves. Based on the developed theoretical interpretation, it has been established that the anomaly in the temperature dependence of the absorption coefficient of a slow transverse wave is associated with the hybridization of impurity d states in the conduction band of the crystal. A comparison of the theoretical and experimental dependences has made it possible to determine the parameters characterizing the hybridized electronic states.
- Published
- 2015
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24. Comparative analysis of existing bone scan formalization and processing methods
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M. N. Sarychev, V. A. Demin, and V. V. Pankin
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Computer science ,Data mining ,computer.software_genre ,computer ,Processing methods - Published
- 2018
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25. Jahn-Teller effect problems via ultrasonic experiments. Application to the impurity crystal CdSe:Cr
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Yu. V. Korostelin, V. V. Gudkov, N. S. Averkiev, M. N. Sarychev, V. T. Surikov, I. V. Zhevstovskikh, Isaac B. Bersuker, Sergei Zherlitsyn, and Shadi Yasin
- Subjects
History ,Materials science ,Jahn–Teller effect ,JAHN-TELLER EFFECT ,02 engineering and technology ,Crystal structure ,01 natural sciences ,Education ,Crystal ,VIBRONIC ENERGY LEVELS ,Normal mode ,DEFORMATION ,0103 physical sciences ,ZINC SULFIDE ,ELECTRONIC GROUND STATE ,010306 general physics ,Elastic modulus ,Wurtzite crystal structure ,Condensed matter physics ,NON-CUBIC CRYSTALS ,Relaxation (NMR) ,CRYSTAL SYMMETRY ,021001 nanoscience & nanotechnology ,II-VI SEMICONDUCTORS ,ULTRASONIC EXPERIMENTS ,Computer Science Applications ,CRYSTAL IMPURITIES ,HEXAGONAL CRYSTALS ,GROUND STATE ,PARTITION FUNCTIONS ,ELASTIC MODULI ,ULTRASONICS ,TEMPERATURE RANGE ,EXPERIMENTAL INVESTIGATIONS ,0210 nano-technology ,Ground state ,METAL IONS ,CADMIUM COMPOUNDS - Abstract
Based on the data analysis of ultrasonic experiments, a novel approach has been developed to explore Jahn-Teller effect (JTE) problems in non-cubic crystals with JT centers without involving additional experimental data beyond the information about the electronic term and crystal symmetry. Distinguished from cubic crystals, the axis of symmetry of the bulk non-cubic crystal do not necessarily coincide with those of the local impurity center, thus complicating the relation between the distortions produced by the ultrasound wave and the JTE active modes. We analysed the problem with corresponding calculations for the wurtzite-type hexagonal crystal CdSe:Cr2+, in which the chromium ion substitutes the cadmium one in the tetrahedral environment, resulting in its electronic ground state 5 T 2(e2t2 ). Experimental investigation of this system by ultrasound at frequencies of 28-105 MHz in the temperature range of 4-180 K, yields a peak in the attenuation of the ultrasound below 40 K for the normal modes related to the c 11, c 44, c 55, c 55, and c 66 elastic moduli. The peak has been interpreted as the manifestation of the JTE, similar to the one, observed in cubic crystals doped with 3d ions. However, no anomalies of attenuation have been detected for the mode related to the c 33 elastic modulus, in contradiction to the theoretical predictions based on the previous method, worked out for cubic crystals. In the new method we obtained direct relations between the deformations, related to the crystal moduli, and the local JT modes, calculated the partition functions for each of the three possible JTE problems for systems with an electronic T term, T⊗e, T⊗t2 and T⊗(e + t2) revealed how these deformations alter the vibronic energy levels responsible for the relaxations in the JT centers. It emerged that in the wurtzite crystal under consideration, only in the T⊗e problem the deformation related to the elastic moduli c 33 displaces all the vibronic energy level uniformly, without relaxation possibilities, thus supporting the new method and explaining the experimental observations.
- Published
- 2018
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26. Ultrasonic exploration of vacancy centres with the Jahn-Teller effect. Application to the ZnSe crystal
- Author
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M. N. Sarychev, A. M. Monakhov, V. V. Gudkov, G.V. Colibaba, K. A. Baryshnikov, V. Yu. Mayakin, D. D. Nedeoglo, V. T. Surikov, Isaac B. Bersuker, I. V. Zhevstovskikh, and N. S. Averkiev
- Subjects
Crystal ,Condensed Matter::Materials Science ,Tetragonal crystal system ,Condensed matter physics ,Chemistry ,Vacancy defect ,Jahn–Teller effect ,Relaxation (NMR) ,Pseudorotation ,Rectangular potential barrier ,Condensed Matter Physics ,Potential energy ,Electronic, Optical and Magnetic Materials - Abstract
We show that the structure, properties, and concentration of vacancies in crystals can be studied by ultrasonic experiments previously employed for impurity centres only. Measurements of the temperature dependence of attenuation and phase velocities of ultrasonic shear waves of 52 MHz propagating along the crystallographic axis [110] of nominally pure ZnSe single crystals (grown by the seeded physical vapour transport method) show strong anomalies which are typical for relaxation processes in system with isolated Jahn–Teller (JT) centres. The observed JT distortion mode is trigonal, subject to a threefold orbitally degenerate T-term interaction with trigonal and tetragonal nuclear displacements. In the absence of sufficiently high concentrations of impurity atoms with such properties we attributed the observed JT centres to zinc vacancies. The temperature dependence of the isothermal and adiabatic forms of the appropriate elastic modulus and the relaxation time show that the relaxation mechanism changes from thermal activation at higher temperatures to tunnelling through a potential energy barrier below 18 K. We provide an estimate of the magnitude of the potential barrier, as well as the pseudorotation frequency and concentration of vacancies. Also we determine the extremum points of the adiabatic potential energy surface of the vacancy centre.
- Published
- 2014
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27. Manifestation of the Jahn-Teller effect in elastic moduli of strontium fluorite crystals doped with chromium ions
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S Zherllitsyn, V. A. Ulanov, I. V. Zhevstovskikh, M. N. Sarychev, Shadi Yasin, G. S. Shakurov, V. V. Gudkov, Isaac B. Bersuker, N. S. Averkiev, and V. T. Surikov
- Subjects
History ,Strontium ,Materials science ,Condensed matter physics ,Jahn–Teller effect ,Relaxation (NMR) ,Strontium fluoride ,Mineralogy ,chemistry.chemical_element ,Atmospheric temperature range ,Cubic crystal system ,Computer Science Applications ,Education ,chemistry.chemical_compound ,chemistry ,Condensed Matter::Strongly Correlated Electrons ,Single crystal ,Elastic modulus - Abstract
Attenuation and phase velocity of ultrasound have been measured in strontium fluoride single crystal doped with chromium in the temperature range of 4 – 185 K at 56 -162 MHz. Anomalies have been found for all the normal modes corresponding to the non-vanishing elastic moduli of a cubic crystal. Interpretation of the observed anomalies has been done in the frame work of relaxation in the system of Jahn-Teller (JT) complexes CrF8 subject to full T2g X (eg+t2g)JT problem. Relaxation time has been calculated from the experimental data on ultrasonic attenuation and adiabatic and isothermal contributions of the impurity subsystem to the total elastic moduli have been obtained.
- Published
- 2017
28. Luminescence spectroscopy of Rb2KTiOF5 oxyfluoride single crystals
- Author
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M. N. Sarychev, V. A. Pustovarov, L. I. Isaenko, and A.V. Kozlov
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Photoluminescence ,Chemistry ,Exciton ,Excited state ,Synchrotron radiation ,Atomic physics ,Luminescence ,Spectroscopy ,Thermoluminescence ,Excitation - Abstract
Spectra of photoluminescence (PL) and X-ray excited luminescence (XRL) in region of 1.5–5.5 eV, PL excitation spectra using synchrotron radiation (3.7–22 eV), time-resolved impulse cathode-luminescence (ICL) spectra, the temperature depending of the XRL, decay kinetics as well as thermoluminescence curves were measured for single crystals Rb2KTiOF5, a promising nonlinear optical material. Single crystals are transparent in microwave, visible and near UV range, inter-band transition energy is Eg = 4.2 eV. Crystalline structure has two disordered mixed position O/F, phase transition in the region of 215 К. All the obtained results indicate that in luminescence spectra nonelementary band 2.2 eV is connected to the emission of self-trapped excitons. Nonelementary band 2.2 eV associated with the presence local distortion in the octahedron TiOF5. It is observed that at interband excitation in VUV region at energies more than 3.5 Eg the effect of multiplication of electronic excitations appears. That determines ...
- Published
- 2017
- Full Text
- View/download PDF
29. Magnetic field induced tunneling and relaxation between orthogonal configurations in solids and molecular systems
- Author
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Shadi Yasin, Sergei Zherlitsyn, Yu. V. Korostelin, K. A. Baryshnikov, V. V. Gudkov, I. V. Zhevstovskikh, M. N. Sarychev, N. S. Averkiev, and Isaac B. Bersuker
- Subjects
Physics ,Quantum decoherence ,Condensed matter physics ,Polyatomic ion ,Relaxation (NMR) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic field ,Orthogonality ,Quantum mechanics ,Excited state ,0103 physical sciences ,Microscopic theory ,010306 general physics ,0210 nano-technology ,Quantum tunnelling - Abstract
We report the effect of magnetic field induced quantum tunneling and relaxation transitions between orthogonal configurations in polyatomic systems where no tunneling is expected. Typical situations of this kind occur in molecular systems and local centers in crystals in ground and excited electronic $T$ states, subject to the $T\ensuremath{\bigotimes}e$ problem of the Jahn-Teller effect, where the wave functions of the three tetragonally distorted configurations are orthogonal. A detailed microscopic theory of this effect shows how the magnetic field violates the orthogonality between the latter allowing for tunneling and relaxations, which decrease in strong fields due to the induced decoherence. The novel effect is demonstrated experimentally as a big, sharp peak in ultrasound attenuation by ${\mathrm{Cr}}^{2+}$ centers in ZnSe:${\mathrm{Cr}}^{2+}$ in the magnetic field $B=0.15$ T at the temperature below 8 K. It may influence a variety of magnetic, electronic, and photonic properties of any system in an electronic $T$ state.
- Published
- 2017
30. Numerical adiabatic potentials of orthorhombic Jahn-Teller effects retrieved from ultrasound attenuation experiments. Application to the SrF2:Cr crystal
- Author
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Sergei Zherlitsyn, N. S. Averkiev, Isaac B. Bersuker, Shadi Yasin, V. T. Surikov, I. V. Zhevstovskikh, M. N. Sarychev, V. A. Ulanov, G. S. Shakurov, and V. V. Gudkov
- Subjects
TEMPERATURE DEPENDENCE ,POLARIZATION ,QUANTUM CHEMISTRY ,Jahn–Teller effect ,ULTRASONIC WAVES ,ADIABATIC POTENTIAL ENERGY SURFACE ,JAHN-TELLER EFFECT ,GROUND VIBRATIONAL STATE ,General Physics and Astronomy ,FOS: Physical sciences ,02 engineering and technology ,POTENTIAL ENERGY ,01 natural sciences ,ULTRASONIC EFFECTS ,0103 physical sciences ,VIBRONIC COUPLING CONSTANTS ,Symmetry breaking ,010306 general physics ,Adiabatic process ,Physics ,TEMPERATURE INTERVALS ,Condensed Matter - Materials Science ,VIBRONIC INTERACTIONS ,Condensed matter physics ,Attenuation ,Materials Science (cond-mat.mtrl-sci) ,021001 nanoscience & nanotechnology ,Polarization (waves) ,Condensed Matter - Other Condensed Matter ,TEMPERATURE DISTRIBUTION ,Molecular vibration ,Potential energy surface ,NUMERICAL RECONSTRUCTION ,ULTRASOUND ATTENUATION ,SHEAR FLOW ,Orthorhombic crystal system ,0210 nano-technology ,Other Condensed Matter (cond-mat.other) - Abstract
A methodology is worked out to retrieve the numerical values of all the main parameters of the six-dimensional adiabatic potential energy surface (APES) of a polyatomic system with a quadratic T-term Jahn-Teller effect (JTE) from ultrasound experiments. The method is based on a verified assumption that ultrasound attenuation and speed encounter anomalies when the direction of propa- gation and polarization of its wave of strain coincides with the characteristic directions of symmetry breaking in the JTE. For the SrF2:Cr crystal, employed as a basic example, we observed anomaly peaks in the temperature dependence of attenuation of ultrasound at frequencies of 50-160 MHz in the temperature interval of 40-60 K for the wave propagating along the [110] direction, for both the longitudinal and shear modes, the latter with two polarizations along the [001] and [110] axes, respectively. We show that these anomalies are due to the ultrasound relaxation by the system of non-interacting Cr2+ JT centers with orthorhombic local distortions. The interpretation of the ex- perimental findings is based on the T2g (eg +t2g) JTE problem including the linear and quadratic terms of vibronic interactions in the Hamiltonian and the same-symmetry modes reduced to one interaction mode. Combining the experimental results with a theoretical analysis we show that on the complicated six-dimensional APES of this system with three tetragonal, four trigonal, and six orthorhombic extrema points, the latter are global minima, while the former are saddle points, and we estimate numerically all the main parameters of this surface, including the linear and quadratic vibronic coupling constants, the primary force constants, the coordinates of all the extrema points and their energies, the energy barrier between the orthorhombic minima, and the tunneling splitting of the ground vibrational states., 8 pages, 3 figures
- Published
- 2016
31. Relaxation and resonance ultrasound attenuation by Jahn-Teller centers in a GaAs:Cu crystal
- Author
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M. N. Sarychev, N. S. Averkiev, A. M. Monakhov, I. V. Zhevstovskikh, K. A. Baryshnikov, V. V. Gudkov, V. E. Sedov, Isaac B. Bersuker, and V. Yu. Mayakin
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Attenuation ,Jahn–Teller effect ,Relaxation (NMR) ,Resonance ,Transverse wave ,Crystal ,Condensed Matter::Materials Science ,Tetragonal crystal system ,Nuclear magnetic resonance ,Condensed Matter::Superconductivity ,Rectangular potential barrier - Abstract
The interaction of ultrasound with Cu Ga4As in a GaAs:Cu crystal has been experimentally studied. The temperature dependences of the attenuation of all normal ultrasonic modes propagating in the 〈110〉 direction both in doped copper and in nominally pure gallium arsenide crystals have been measured. In the GaAs:Cu crystal, the attenuation peak has been revealed for a transverse wave polarized along the 〈110〉 axis whose elastic shifts correspond to the symmetry of the tetragonal mode of the Jahn-Teller effect. The temperature dependence of the attenuation of this wave indicates that two types of attenuation-relaxation and resonance-occur. The constructed temperature dependence of the relaxation time indicates that tunneling through the potential barrier between the minima of the adiabatic potential energy is the main relaxation mechanism at temperatures below 10 K. Tunneling splitting estimated from experimental data is in good agreement with the theoretical estimate. © 2012 Pleiades Publishing, Ltd.
- Published
- 2012
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32. Anomalous Behavior of the Elastic and Optical Properties in Bi1.5 Sb0.5 Te1.8 Se1.2 Topological Insulator Induced by Point Defects
- Author
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Oleg E. Tereshchenko, T. V. Kuznetsova, V. V. Gudkov, I. V. Zhevstovskikh, M. N. Sarychev, Konstantin A. Kokh, Yuri S. Ponosov, N. S. Averkiev, and Svetlana G. Titova
- Subjects
Materials science ,Condensed matter physics ,Ultrasound attenuation ,02 engineering and technology ,Anomalous behavior ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Crystallographic defect ,Electronic, Optical and Magnetic Materials ,symbols.namesake ,Topological insulator ,0103 physical sciences ,symbols ,010306 general physics ,0210 nano-technology ,Raman spectroscopy ,Elastic modulus - Published
- 2018
- Full Text
- View/download PDF
33. Acoustic Properties of Crystals with Jahn–Teller Impurities: Elastic Moduli and Relaxation Time. Application to SrF2:Cr2+
- Author
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Shadi Yasin, V. V. Gudkov, Vladimir A. Ulanov, N. S. Averkiev, I. V. Zhevstovskikh, G. S. Shakurov, Sergei Zherlitsyn, Vladimir T. Surikov, M. N. Sarychev, and Isaac B. Bersuker
- Subjects
Materials science ,Condensed matter physics ,Jahn–Teller effect ,Relaxation (NMR) ,General Physics and Astronomy ,02 engineering and technology ,Activation energy ,021001 nanoscience & nanotechnology ,01 natural sciences ,Moduli ,Vibronic coupling ,Impurity ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,0210 nano-technology ,Adiabatic process ,Elastic modulus - Abstract
A new approach to evaluate the relaxation contribution to the total elastic moduli for crystals with Jahn–Teller (JT) impurities is worked out and applied to the analysis of the experimentally measured ultrasound velocity and attenuation in SrF2:Cr2+. Distinguished from previous work, the background adiabatic contribution to the moduli, important for revealing the impurity relaxation contribution, is taken into account. The temperature dependence of the relaxation time for transitions between the equivalent configurations of the JT centers has been obtained, and the activation energy for the latter in SrF2:Cr2+, as well as the linear vibronic coupling constant have been evaluated.
- Published
- 2017
- Full Text
- View/download PDF
34. Ultrasonic investigation of the Jahn-Teller effect in GaAs semiconductors doped by transition metals
- Author
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V. V. Gudkov, M. N. Sarychev, K. A. Baryshnikov, V. E. Sedov, V. T. Surikov, N. S. Averkiev, Isaac B. Bersuker, I. V. Zhevstovskikh, V. Yu. Mayakin, and A. M. Monakhov
- Subjects
TEMPERATURE DEPENDENCE ,Materials science ,Jahn–Teller effect ,JAHN-TELLER EFFECT ,General Physics and Astronomy ,Dielectric ,THERMAL ACTIVATION MECHANISMS ,GROUND-STATE ENERGIES ,STABILIZATION ENERGY ,STRUCTURE AND PROPERTIES ,CRYSTAL STRUCTURE ,Crystal ,Impurity ,ULTRASONIC INVESTIGATIONS ,Condensed Matter::Superconductivity ,ULTRASONIC TESTING ,SHEAR WAVES ,Elastic modulus ,TEMPERATURE INTERVALS ,Condensed matter physics ,Doping ,Relaxation (NMR) ,IMPURITIES ,TRANSITION METALS ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,CRYSTAL IMPURITIES ,GROUND STATE ,TEMPERATURE DISTRIBUTION ,SEMICONDUCTING GALLIUM ,SHEAR FLOW ,GALLIUM ARSENIDE ,Condensed Matter::Strongly Correlated Electrons ,TUNNELING SPLITTINGS ,Phase velocity ,POINT DEFECTS - Abstract
Transition-metal-doped semiconductor GaAs crystals are used as model systems for spintronic research, as well as in other applications. To explore the structure and properties of such impurities, we extended the methodology of ultrasonic investigation of the Jahn-Teller effect in dielectric impurity-centers to the study of significantly different semiconductor impurities using the GaAs:Cu crystal as an example. Phase velocity and attenuation of ultrasound in this system were measured in the temperature interval of 1.9-80 K at 52 MHz and 156 MHz. The anomaly in the velocity and a peak of attenuation found for the longitudinal and slow shear waves indicate the presence of the Jahn-Teller effect with the e-type local distortions of the CuGa4As impurity complex. The temperature dependence of the elastic modulus and relaxation time shows that below 5 K, the thermal activation mechanism of relaxation is possibly replaced by resonance type transitions. The main parameters of the Jahn-Teller effect, stabilization energy, minima positions and the barrier between them, frequency of pseudorotation of the distortions, and the tunneling splitting of the ground state energy, as well as the constant of exchange interaction between the two holes in Cu2+ centers and the concentration of the centers were estimated. © 2014 AIP Publishing LLC. Russian Foundation for Basic Research, RFBR
- Published
- 2014
35. Magnetoacoustic investigation of the Jahn-Teller effect in chromium doped ZnSe crystal
- Author
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V. V. Gudkov, A.A. Suvorov, V.Y. Mayakin, Sergei Zherlitsyn, Shadi Yasin, Isaac B. Bersuker, I. V. Zhevstovskikh, and M. N. Sarychev
- Subjects
Materials science ,Condensed matter physics ,CRYSTAL ,Attenuation ,Jahn–Teller effect ,Doping ,JAHN-TELLER EFFECT ,TRANSITION METAL IMPURITY ,chemistry.chemical_element ,ZINC-BLENDE STRUCTURE ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Magnetic field ,Crystal ,Chromium ,chemistry ,Wavenumber ,General Materials Science ,Ultrasonic sensor ,ULTRASOUND - Abstract
Ultrasonic investigation of ZnSe:Cr2+crystal was carried out at low temperatures in magnetic field applied along the wave vector. The observed anomalies in magnetic field dependences of attenuation and wave number evidence for existence of resonant transitions between the energy levels of the Jahn-Teller tetrahedral complex CrSe4.
- Published
- 2012
36. Jahn-Teller effect problems via ultrasonic experiments. Application to the impurity crystal CdSe:Cr.
- Author
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N S Averkiev, I B Bersuker, V V Gudkov, I V Zhevstovskikh, M N Sarychev, S Zherlitsyn, S Yasin, Yu V Korostelin, and V T Surikov
- Published
- 2019
- Full Text
- View/download PDF
37. Dynamic tests of multi-detector radiometric system on central blood circulation phantom.
- Author
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A D Krotov, S V Pankin, A I Surdo, V V Pankin, M N Sarychev, A A Schelkanov, and A V Zelenin
- Published
- 2018
- Full Text
- View/download PDF
38. Manifestation of the Jahn-Teller effect in elastic moduli of strontium fluorite crystals doped with chromium ions.
- Author
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N S Averkiev, I B Bersuker, V V Gudkov, I V Zhevstovskikh, M N Sarychev, S Zherllitsyn, S Yasin, G S Shakurov, V A Ulanov, and V T Surikov
- Published
- 2017
- Full Text
- View/download PDF
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