77 results on '"R. A. Lunin"'
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2. Preparation and superconducting behavior of triammonium fulleride
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Boris M. Bulychev, R. A. Lunin, Yan V. Zubavichus, Nikolai S. Ezhikov, Roman Svetogorov, and V. A. Kulbachinskii
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Materials science ,Ionic radius ,Fullerene ,Rietveld refinement ,02 engineering and technology ,General Chemistry ,Crystal structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Crystallography ,Lattice constant ,Octahedron ,Phase (matter) ,General Materials Science ,0210 nano-technology ,Solid solution - Abstract
The synthesis of triammonium fulleride (NH4)3C60 by ion exchange of either K3C60 or Rb3C60 with NH4Cl in absolute toluene is reported. According to the Rietveld refinement of a synchrotron radiation-based X-ray diffraction pattern, (NH4)3C60 belongs to the same structure type as both K3C60 and Rb3C60 featuring an fcc lattice with intercalated cations occupying tetrahedral and octahedral cavities of the close-packing formed by fullerene С60 spheres. The ion exchange is incomplete and the final formulation of the product is [(NH4)2.88K0.12]C60. In contrast to earlier suggestions and tabulated ionic radii values, the (NH4)3C60 crystal structure is characterized by a lattice parameter slightly smaller than that of K3C60. A similar reaction between K4C60 and NH4Cl proceeds differently involving the redox step and affords [(NH4)0.48K2.52]C60 again emphasizing the fact that ammonium and potassium in the fulleride phase tend to form substitutional solid solutions. According to low-frequency inductive method, all (NH4)3C60-related phases studied are superconducting with similar temperatures of the superconducting transition around Tc = 16.4 K. more...
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- 2021
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3. Synthesis and superconductivity of organometallic fullerides M(3−n)(NR4)(n)C60, where M = K, Rb; R = H, D, Me, Et, Bu; n = 1, 2, 3
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Nikolai S. Ezhikov, V. A. Kulbachinskii, Boris M. Bulychev, and R. A. Lunin
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010302 applied physics ,Physics and Astronomy (miscellaneous) ,Hydrogen ,General Physics and Astronomy ,chemistry.chemical_element ,Halide ,Alkali metal ,01 natural sciences ,Toluene ,chemistry.chemical_compound ,chemistry ,Deuterium ,0103 physical sciences ,Kinetic isotope effect ,Physical chemistry ,Ammonium ,010306 general physics ,Tetrahydrofuran - Abstract
We present experimental data on the synthesis and investigation of the superconducting and structural properties of organometallic fullerides M(3−n)(NR4)(n)C60, where M = K, Rb; R = hydrogen H, deuterium D, methyl Me, ethyl Et, butyl Bu; n = 1, 2, 3, synthesized by exchange reactions of homofullerides of alkali metals of composition K3C60 and Rb3C60 with ammonium halides in the medium of absolute toluene or tetrahydrofuran (THF) at temperatures from 23°C to 110°C. We have studied also superconductivity in Rb2NH4C60 and Rb2ND4C60 samples with replacement of hydrogen for deuterium in ammonium, as well as in K2NH4C60 and K2ND4C60. The superconducting transition temperature did not change with replacement H by D within the measurement accuracy. more...
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- 2021
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4. Superconductivity of potassium and rubidium heterofullerides modified with low-melting alloys
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V. A. Kulbachinskii, R. A. Lunin, Nikolai S. Ezhikov, and Boris M. Bulychev
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010302 applied physics ,Superconductivity ,Materials science ,Physics and Astronomy (miscellaneous) ,Organic solvent ,Potassium ,Melting temperature ,Alloy ,Analytical chemistry ,General Physics and Astronomy ,Y alloy ,chemistry.chemical_element ,engineering.material ,01 natural sciences ,Toluene ,Rubidium ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,engineering ,010306 general physics - Abstract
The paper provides experimental data on the synthesis and study of the superconducting properties of potassium and rubidium heterofullerides modified by Wood’s alloy — Sn, Pb, Bi, Cd (hereinafter W) with a melting temperature Tm = 61.5 °C or Y alloy — Bi, Sn, Pb, In, Cd, Tl with Tm = 41.5 °C. The synthesis of heterofullerides was carried out by the interaction of fullerides of the composition K2C60 and Rb2C60, which do not have superconducting properties, with one of the alloys W or Y in an organic solvent — toluene at 100–110 °C. The samples obtained in this case showed superconducting properties with Tc = 8 K for K2YC60 and Rb2WC60 and 16 K for K2WC60. more...
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- 2021
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5. Superconductivity in alkali-doped fullerides with wood’s metal and heterofullerides with two different alkali metals A(1)A(2)MC60
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V. A. Kulbachinskii, Nikolai S. Ezhikov, R. A. Lunin, and Boris M. Bulychev
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Superconductivity ,Materials science ,Organic Chemistry ,Inorganic chemistry ,Doping ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Alkali metal ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Wood's metal ,General Materials Science ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
Here we report our experimental data on the synthesis and investigation of superconductivity in fullerides and heterofullerides synthesized by different methods and also doped by alloys wit...
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- 2019
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6. Thermoelectric properties, Shubnikov–de Haas effect and mobility of charge carriers in bismuth antimony tellurides and selenides and nanocomposite based on these materials
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V. A. Kulbachinskii, Arnab Banerjee, R. A. Lunin, A. A. Kudryashov, and Vladimir G. Kytin
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Electron mobility ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,business.industry ,Doping ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Shubnikov–de Haas effect ,Bismuth ,Semiconductor ,chemistry ,Seebeck coefficient ,0103 physical sciences ,Thermoelectric effect ,Charge carrier ,010306 general physics ,0210 nano-technology ,business - Abstract
We describe here the study of the Shubnikov–de Haas effect and thermoelectric properties of p-(Bi0.5Sb0.5)2Te3 single crystals doped with Ga, n-Bi2–xTlxSe3 and p-Sb2–xTlxTe3. Using Fourier spectra of the oscillations we calculated the mobility of charge carriers and its variation upon doping. We found that Ga has a donor effect in p-(Bi0.5Sb0.5)2Te3, Tl is an acceptor in n-Bi2–xTlxSe3 and increases the mobility of electrons, while in p-Sb2–xTlxTe3, Tl is a donor and decreases the mobility of holes. We consider the evolution of the defectiveness of crystals that leads to the observed effects. We also synthesized and investigated nanocomposites of solid solutions Sb2Te3–xSex (0 more...
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- 2017
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7. Effect of thallium doping on the mobility of electrons in Bi2Se3 and holes in Sb2Te3
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A. A. Kudryashov, Aritra Banerjee, V. A. Kulbachinskii, Vladimir G. Kytin, and R. A. Lunin
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010302 applied physics ,Electron mobility ,Condensed matter physics ,Doping ,Electron concentration ,chemistry.chemical_element ,02 engineering and technology ,Electron ,Fourier spectrum ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Crystal ,chemistry ,Hall effect ,0103 physical sciences ,Thallium ,0210 nano-technology - Abstract
The Shubnikov–de Haas effect and the Hall effect in n-Bi2–x Tl x Se3 (x = 0, 0.01, 0.02, 0.04) and p-Sb2–x Tl x Te3 (x = 0, 0.005, 0.015, 0.05) single crystals are studied. The carrier mobilities and their changes upon Tl doping are calculated by the Fourier spectra of oscillations. It is found shown that Tl doping decreases the electron concentration in n-Bi2–x Tl x Se3 and increases the electron mobility. In p-Sb2–x Tl x Te3, both the hole concentration and mobility decrease upon Tl doping. The change in the crystal defect concentration, which leads to these effects, is discussed. more...
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- 2016
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8. Electron Mobilities and Effective Masses in InGaAs/InAlAs HEMT Structures with High In Content
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L. N. Oveshnikov, N. A. Yuzeeva, A. V. Sorokoumova, V. A. Kulbachinskii, E. A. Klimov, D. V. Lavruchin, G. B. Galiev, and R. A. Lunin
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010302 applied physics ,Physics ,Photoluminescence ,Condensed matter physics ,Doping ,02 engineering and technology ,Electron ,High-electron-mobility transistor ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Effective mass (solid-state physics) ,0103 physical sciences ,General Materials Science ,0210 nano-technology ,Electronic band structure ,Quantum well ,Molecular beam epitaxy - Abstract
In $$_{x}$$ Ga $$_{1-{x}}$$ As/In $$_{y}$$ Al $$_{1-{y}}$$ As HEMT structures $${\updelta }$$ -doped by Si were grown by molecular beam epitaxy on InP substrate. We investigated the influence of the In content on the electron mobilities and effective masses in dimensionally quantized subbands. The electron effective masses were determined by the temperature dependence of the amplitude of the Shubnikov–de Haas effect at 1.6 and 4.2 K. We found that the more the In content in quantum well (QW), the less the electron effective masses. The mobilities are higher in HEMT structures with wider and deeper QW. The energy band diagrams were calculated by using Vegard’s law for basic parameters. The calculated band diagrams are in a good agreement with the experimental data of photoluminescence spectra. more...
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- 2016
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9. Superconductivity of Fullerides with Composition AGa $$_{x}$$ x C $$_{60}$$ 60 and AGa $$_{x}$$ x M $$_{y}$$ y C $$_{60}$$ 60 (A = K, Rb; M = In, Sn, Bi)
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V. A. Kulbachinskii, R. A. Lunin, Yu. A. Velikodny, and Boris M. Bulychev
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Physics ,Superconductivity ,Condensed matter physics ,02 engineering and technology ,Crystal structure ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Magnetic susceptibility ,Atomic and Molecular Physics, and Optics ,Crystallography ,0103 physical sciences ,General Materials Science ,Orthorhombic crystal system ,010306 general physics ,0210 nano-technology - Abstract
The new heterofullerides with the composition AGa $$_{x}$$ C $$_{60}$$ and AGa $$_{x}$$ M $$_{y}$$ C $$_{60}$$ (A = K, Rb; M = In, Sn, Bi; $$x,y
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- 2016
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10. Superconductivity of heterofullerides with one or two atoms of the alkali metals and gallium, indium, bismuth or tin
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Yu. A. Velikodny, Boris M. Bulychev, R. A. Lunin, and V. A. Kulbachinskii
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Superconductivity ,Inorganic chemistry ,Intercalation (chemistry) ,chemistry.chemical_element ,Alkali metal ,Magnetic susceptibility ,Bismuth ,Inorganic Chemistry ,Crystallography ,chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,Gallium ,Tin ,Indium - Abstract
The new superconducting heterofullerides with the composition AnGaxC60 and AnGaxMyC60 (A = K, Rb; n = 1, 2; M = In, Sn, Bi; x, y
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- 2015
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11. Influence of buffer-layer construction and substrate orientation on the electron mobilities in metamorphic In0.70Al0.30As/In0.76Ga0.24As/In0.70Al0.30As structures on GaAs substrates
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E. A. Klimov, R. A. Lunin, P. P. Maltsev, G. B. Galiev, V. A. Kulbachinskii, L. N. Oveshnikov, S. S. Pushkarev, and N. A. Yuzeeva
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Electron mobility ,Condensed matter physics ,Misorientation ,Hall effect ,Electrical resistivity and conductivity ,Chemistry ,Substrate (electronics) ,Atmospheric temperature range ,Condensed Matter Physics ,Anisotropy ,Atomic and Molecular Physics, and Optics ,Shubnikov–de Haas effect ,Electronic, Optical and Magnetic Materials - Abstract
The influence of construction of the buffer layer and misorientation of the substrate on the electrical properties of In0.70Al0.30As/In0.76Ga0.24As/In0.70Al0.30As quantum wells on a GaAs substrate is studied. The temperature dependences (in the temperature range of 4.2 K < T < 300 K) and field dependences (in magnetic fields as high as 6 T) of the sample resistances are measured. Anisotropy of the resistances in different crystallographic directions is detected; this anisotropy depends on the substrate orientation and construction of the metamorphic buffer layer. In addition, the Hall effect and the Shubnikov–de Haas effect are studied. The Shubnikov–de Haas effect is used to determine the mobilities of electrons separately in several occupied dimensionally quantized subbands in different crystallographic directions. The calculated anisotropy of mobilities is in agreement with experimental data on the anisotropy of the resistances. more...
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- 2015
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12. Experimental determination of the electron effective masses and mobilities in each dimensionally-quantized subband in an In x Ga1 − x As quantum well with InAs inserts
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P. P. Maltsev, L. N. Oveshnikov, R. A. Lunin, N. A. Yuzeeva, E. A. Klimov, G. B. Galiev, and V. A. Kulbachinskii
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Electron mobility ,Condensed matter physics ,Chemistry ,High-electron-mobility transistor ,Electron ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Shubnikov–de Haas effect ,Electronic, Optical and Magnetic Materials ,Effective mass (solid-state physics) ,Fermi gas ,Quantum well ,Molecular beam epitaxy - Abstract
HEMT structures with In0.53Ga0.47As quantum well are synthesized using molecular-beam epitaxy on InP substrates. The structures are double-side Si δ-doped so that two dimensionally-quantized subbands are occupied. The effect of the central InAs nanoinsert in the quantum well on the electron effective masses m* and mobilities in each subband is studied. For experimental determination of m*, the quantum μ q and transport μ t mobilities of the two-dimensional electron gas in each dimensionally-quantized subband, the Shubnikov-de Haas effect is measured at two temperatures of 4.2 and 8.4 K. The electron effective masses are determined by the temperature dependence of the oscillation amplitudes, separating the oscillations of each dimensionally-quantized subband. The Fourier spectra of oscillations are used to determine the electron mobilities μ q and μ t in each dimensionally-quantized subband. It is shown that m* decreases as the InAs-nanoinsert thickness d in the In0.53Ga0.47As quantum well and electron mobilities increase. The maximum electron mobility is observed at the insert thickness d = 3.4 nm. more...
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- 2015
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13. Persistent photoconductivity and electron mobility in In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As/InP quantum-well structures
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V. A. Kulbachinskii, R. A. Lunin, G. B. Galiev, I.S. Vasilievskii, N. A. Yuzeeva, and E. A. Klimov
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Electron mobility ,Condensed matter physics ,Chemistry ,Scattering ,Photoconductivity ,Electron ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Shubnikov–de Haas effect ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Atomic electron transition ,Condensed Matter::Strongly Correlated Electrons ,Electron scattering ,Quantum well - Abstract
The influence of the width of the quantum well L and doping on the band structure, scattering, and electron mobility in nanoheterostructures with an isomorphic In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As quantum well grown on an InP substrate are investigated. The quantum and transport mobilities of electrons in the dimensionally quantized subbands are determined using Shubnikov-de Haas effect measurements. These mobilities are also calculated for the case of ionized-impurity scattering taking into account intersub-band electron transitions. It is shown that ionized-impurity scattering is the dominant mechanism of electron scattering. At temperatures T < 170 K, persistent photoconductivity is observed, which is explained by the spatial separation of photoexcited charge carriers. more...
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- 2013
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14. Electron mobilities in isomorphic In0.53Ga0.47As quantum wells on InP substrates
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I. S. Vasil’evskii, G. B. Galiev, E. A. Klimov, V. A. Kulbachinskii, N. A. Yuzeeva, and R. A. Lunin
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Electron mobility ,Quantization (physics) ,Materials science ,Condensed matter physics ,Scattering ,Band diagram ,General Physics and Astronomy ,Electronic structure ,Electron ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Quantum well ,Shubnikov–de Haas effect - Abstract
The influence of the doping level, illumination, and width of isomorphic In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As quantum wells grown on InP substrates on the electron mobility is studied. The persistent photoconductivity at low temperatures is found. Band diagrams are calculated and optimal parameters are found for obtaining the maximum electron mobility. The quantum and transport electron mobilities in dimensional quantization subbands are obtained from the Shubnikov-de Haas effect. The electron mobilities are calculated in dimensional quantization subbands upon scattering by ionized impurities taking intersubband transitions into account. Scattering by ionized impurities in samples studied is shown to be dominant at low temperatures. more...
- Published
- 2013
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15. Enhancement of Electron Mobility and Photoconductivity in Quantum Well In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As οn InP Substrate
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I.S. Vasilievskii, G. B. Galiev, R. A. Lunin, V. A. Kulbachinskii, N. A. Yuzeeva, and E.A. Klimov
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Electron mobility ,Materials science ,Condensed matter physics ,business.industry ,Photoconductivity ,Doping ,Electron concentration ,General Physics and Astronomy ,Substrate (electronics) ,Electron transport chain ,Optoelectronics ,business ,Quantum well ,Molecular beam epitaxy - Abstract
Isomorphic In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As quantum well structure on InP substrate were grown by molecular beam epitaxy. We investigated the electron transport properties and mobility enhancement in the structures by changing of doping level, the width d of quantum well In0.53Ga0.47As or by illumination using light with λ = 668 nm. Persistent photoconductivity was observed in all samples due to spatial separation of carriers. We used the Shubnikov de Haas e ect to analyze subband electron concentration and mobility. The maximal mobility was observed for quantum well width d = 16 nm. more...
- Published
- 2013
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16. Superconducting properties of new heterofullerides
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R. A. Lunin, Boris M. Bulychev, V. A. Kulbachinskii, I. P. Kachan, Yu. A. Velikodnyi, and V. P. Tarasov
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Superconductivity ,Materials science ,Physics and Astronomy (miscellaneous) ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,law.invention ,symbols.namesake ,Nuclear magnetic resonance ,chemistry ,Solid-state nuclear magnetic resonance ,law ,X-ray crystallography ,symbols ,Raman spectroscopy ,Electron paramagnetic resonance ,Boron ,Raman scattering ,Indium - Abstract
Superconducting properties of new heterofullerides synthesized for the first time AnMmHgxC60 (A = K, Rb, Cs; M = Be, Mg, B, Al, Ga, In; n = 1, 2; m = 1, 2; x ≪ 1) were investigated at low temperatures. The low frequency inductive method was used to detect a superconducting transition. All the samples were studied by X-ray diffraction (XRD), solid state nuclear magnetic resonance (NMR), electron spin resonance (ESR), and Raman scattering. It is found that most of the superconducting heterofullerides are potassium heterofullerides. For the fulleride K2GaHgxC60 the critical temperature of the superconducting transition is Tc = 20 K. Indium and boron heterofullerides are not superconductors. The synthesis of heterofullerides via amalgams (Hg–K–Mg, Hg–Rb–Al) gives rise to two different superconducting phases. more...
- Published
- 2013
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17. Influence of Sn on the thermoelectric properties of (BixSb1−x)2Te3 single crystals
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V. A. Kulbachinskii, A. A. Kudryashov, R. A. Lunin, and Vladimir G. Kytin
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Materials science ,Condensed matter physics ,Doping ,chemistry.chemical_element ,Atmospheric temperature range ,Condensed Matter Physics ,Thermoelectric materials ,Electronic, Optical and Magnetic Materials ,Inorganic Chemistry ,Thermal conductivity ,chemistry ,Electrical resistivity and conductivity ,Seebeck coefficient ,Thermoelectric effect ,Materials Chemistry ,Ceramics and Composites ,Physical and Theoretical Chemistry ,Tin - Abstract
The influence of tin on the thermoelectric properties of p-(BixSb1−x)2Te3 single crystals (x=0; 0.25; 0.5) has been investigated. The temperature dependence of the Seebeck coefficient S, the electrical conductivity σ, the heat conductivity k and the thermoelectric figure of merit of p-(BixSb1−x)2Te3 single crystals were measured in the temperature range 7–300 K. By an increase the Sn content, the hole concentration increases in p-(BixSb1−x)2−ySnyTe3. The heat conductivity k of the p-(BixSb1−x)2−ySnyTe3 crystals decreases due to the Sn doping, while the electrical conductivity σ increases in the temperature interval about 200 more...
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- 2012
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18. Structure and properties of solid solutions in the Mg-Al-B system
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O. K. Gulish, V. P. Tarasov, Vladimir K. Genchel, R. A. Lunin, O. V. Kravchenko, L.G. Sevastyanova, V. A. Stupnikov, and Boris M. Bulychev
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Superconductivity ,Materials science ,superconductivity ,Physics ,QC1-999 ,Analytical chemistry ,General Physics and Astronomy ,Mole fraction ,chemistry.chemical_compound ,chemistry ,Electrical resistivity and conductivity ,magnesium diboride ,Phase (matter) ,visual_art ,Magnesium diboride ,visual_art.visual_art_medium ,Ceramic ,superstructure ,Superstructure (condensed matter) ,Solid solution - Abstract
Compounds with the general formula Mg1−x Al x B2 were obtained by two-step ceramic synthesis. All compounds were characterized by X-ray diffraction, NMR spectroscopy, and by four point probe resistivity measurements in various magnetic fields method. The diborides unit cell parameters were determined as a function of the Al mole fraction. With the vaues of x up to 0.40 (where x is the composition of the stock prepared for sintering), the unit cell parameters of Mg1−x Al x B2 are similar to those of pure MgB2 and the superconducting transition temperature was lowered. For stock compositions of 0:25 ≤ x ≤ 0:60, the products contain a superstructure, also superconducting phase, which becomes the only product at x = 0:50, and at x > 0:60 this phase is replaced by AlB2-based solid solutions. more...
- Published
- 2012
19. Scattering and electron mobility in combination-doped HFET-structures AlGaAs/InGaAs/AlGaAs with high electron density
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I. S. Vasil’evskii, Dmitry Ponomarev, Rustam A. Khabibullin, R. A. Lunin, G. B. Galiev, V. A. Kulbachinskii, and E. A. Klimov
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Electron density ,Electron mobility ,Materials science ,Condensed matter physics ,Doping ,Heterojunction ,Electron ,Condensed Matter Physics ,Epitaxy ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Condensed Matter::Superconductivity ,Condensed Matter::Strongly Correlated Electrons ,Quantum well ,Molecular beam epitaxy - Abstract
Molecular-beam epitaxy is used for growing structures differing in doping technique and doping level and having a high two-dimensional-electron concentration n s in the quantum well. The effect of doping combining uniform and δ doping on the electron-transport properties of heterostructures is investigated. A new type of structure with a two-sided silicon δ doping of GaAs transition layers located on the quantum-well boundaries is proposed. The largest value of electron mobility μH = 1520 cm2/(V s) is obtained simultaneously with a high electron density n s = 1.37 × 1013 cm−2 at 300 K with such a doping. It is associated with decreasing electron scattering by an ionized impurity, which is confirmed by the carried out calculations. more...
- Published
- 2011
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20. Superconductivity and spectroscopy of homo- and heterofullerides of alkali metals and thallium
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Vladimir G. Kytin, Boris M. Bulychev, R. A. Lunin, and V. A. Kulbachinskii
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Superconductivity ,Materials science ,High-temperature superconductivity ,Physics and Astronomy (miscellaneous) ,Transition temperature ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,law.invention ,symbols.namesake ,Nuclear magnetic resonance ,Differential scanning calorimetry ,chemistry ,law ,X-ray crystallography ,symbols ,Thallium ,Electron paramagnetic resonance ,Raman spectroscopy - Abstract
Liquid alloys of metals with mercury (amalgams) are used to synthesize the fullerides AnHgxC60 (A=K,Rb,Cs; n=2;3; x
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- 2011
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21. Superconductivity of Fullerides AnHgxC60(A = K,Rb,Cs; n = 2,3) Synthesized from Amalgams
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Boris M. Bulychev, R. A. Lunin, Vladimir G. Kytin, V. A. Kulbachinskii, and Yu. A. Velikodny
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Superconductivity ,Condensed matter physics ,Chemistry ,Transition temperature ,Organic Chemistry ,X-ray ,Fermi energy ,Atomic and Molecular Physics, and Optics ,law.invention ,Crystallography ,law ,Lattice (order) ,General Materials Science ,Orthorhombic crystal system ,Physical and Theoretical Chemistry ,Electron paramagnetic resonance ,Monoclinic crystal system - Abstract
The fullerides AnHgxC60 (A = K,Rb,Cs; n = 2,3; x
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- 2010
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22. Investigation of Paramagnetic Centers in Fullerides A2MC60 and AM2C60 (A = K, Rb, M = Mg, Be)
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R. A. Lunin, Elizaveta A. Konstantinova, Vladimir G. Kytin, A. V. Krechetov, Boris M. Bulychev, and V. A. Kulbachinskii
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Paramagnetism ,Nuclear magnetic resonance ,Spins ,Solid-state physics ,law ,Chemistry ,Analytical chemistry ,Electron ,Absorption (chemistry) ,Electron paramagnetic resonance ,Thermal conduction ,Atomic and Molecular Physics, and Optics ,law.invention - Abstract
Paramagnetic centers in heterofullerides with the composition A2MC60 and AM2C60 (A = K, Rb, M = Mg, Be) were investigated by the electron spin resonance (ESR) method. It was found that the ESR signal can be interpreted as a composition of two lines with different temperature dependence of ESR absorption magnitude. This gives an evidence of the presence of at least two different types of paramagnetic centers. Centers of the first type behave as localized spins, while the rest can be interpreted as conduction electrons. more...
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- 2008
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23. Study of the paramagnetic centers in heterofullerides MnM′3-nC60 (M = K, Rb, Cs; M′ = Be, Mg, Ca, Ba; n = 1, 2)
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Vladimir G. Kytin, Boris M. Bulychev, R. A. Lunin, Elizaveta A. Konstantinova, Yu. A. Velikodnyi, V. A. Kulbachinskii, and A. V. Krechetov
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Superconductivity ,Condensed matter physics ,Materials Science (miscellaneous) ,Analytical chemistry ,chemistry.chemical_element ,Electron ,Atmospheric temperature range ,Thermal conduction ,Oxygen ,Electronic states ,law.invention ,Inorganic Chemistry ,Paramagnetism ,chemistry ,law ,Physical and Theoretical Chemistry ,Electron paramagnetic resonance - Abstract
New heterofullerides Cs2MC60, CsM2C60, Rb2MC60, K2MC60, and KM2C60 (M = Be, Mg, Ca, Ba) have been synthesized; the temperature dependences of the magnetic susceptibilities of these compounds in the temperature range from 4.2 to 297 K have been measured. Among these heterofullerides, K2MgC60, KMg2C60, K2CaC60, K2BeC60, and Rb2BeC60 pass to the superconducting state at temperatures Tc = 13–24.3 K. The paramagnetic electronic states of the compounds have been studied by EPR at temperatures of 105–300 K, which shows the existence of two types of paramagnetic centers, related to oxygen defects and conduction electrons. more...
- Published
- 2008
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24. Superconductivity, Electron Paramagnetic Resonance, and Raman Scattering Studies of Heterofullerides with Cs and Mg
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Vladimir G. Kytin, V. A. Kulbachinskii, R. A. Lunin, Elizaveta A. Konstantinova, Boris M. Bulychev, and A. V. Krechetov
- Subjects
Superconductivity ,Materials science ,Article Subject ,Condensed matter physics ,Condensed Matter Physics ,lcsh:QC1-999 ,law.invention ,symbols.namesake ,chemistry.chemical_compound ,Metal halides ,chemistry ,law ,Anhydrous ,symbols ,Physical chemistry ,Electron paramagnetic resonance ,lcsh:Physics ,Raman scattering - Abstract
In the present study, the results of investigation of physical properties of heterofulleridesA3−xMxC60(A=K, Rb, Cs, M=Be, Mg, Ca, Al, Fe, Tl,x=1,2); as well asRbCsTlC60,KCsTlC60, andKMg2C60are described. All of the fullerides were synthesized by the exchange reactions of alkaline fullerides with anhydrous metal halides. Superconductivity was found inRbCsTlC60andKCsTlC60. more...
- Published
- 2008
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25. New metal-rich mixed chalcogenides with an intergrowth structure: Ni5.68SiSe2, Ni5.46GeSe2, and Ni5.42GeTe2
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Michael Ruck, B. A. Popovkin, R. A. Lunin, Th. Doert, V. A. Kulbachinskii, Anna Isaeva, and Alexey Baranov
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chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Crystal structure ,Metal ,Nickel ,Chalcogen ,Crystallography ,Tetragonal crystal system ,chemistry ,Electrical resistivity and conductivity ,visual_art ,visual_art.visual_art_medium ,Ceramic ,Isostructural - Abstract
New metal-rich mixed nickel-silicon and nickel-germanium chalcogenides, Ni5.68SiSe2, Ni5.46GeSe2, and Ni5.42GeTe2, were synthesized by high-temperature ceramic techniques. The X-ray diffraction study of single crystals grown from a molten flux revealed that the compounds are isostructural and crystallize in the tetragonal system (space group I4/mmm, Z = 2). These compounds are the first members of the family of M7−δEX2-type (M = Ni or Pd; E = Sn or Sb; X is chalcogen) intergrowth structures containing “light” p elements E. Resistivity measurements on pressed textured pellets showed that both selenides are anisotropic metallic conductors in the directions parallel and perpendicular to the heterometallic bond systems. The geometric criteria of stability of the intergrowth structure type under consideration are discussed. more...
- Published
- 2007
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26. Electron transport and optical properties of shallow GaAs/InGaAs/GaAs quantum wells with a thin central AlAs barrier
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G. Galistu, A. de Visser, V. A. Kulbachinskii, V. G. Mokerov, S. S. Shirokov, I. S. Vasil’evskii, G. B. Galiev, and R. A. Lunin
- Subjects
Physics ,Photoluminescence ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Condensed Matter::Other ,Doping ,FOS: Physical sciences ,Electron ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Condensed Matter::Materials Science ,Electrical resistivity and conductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Materials Chemistry ,Electrical and Electronic Engineering ,Wave function ,Quantum well ,Envelope (waves) - Abstract
Shallow GaAs/InGaAs/GaAs quantum well structures with and without a three monolayer thick AlAs central barrier have been investigated for different well widths and Si doping levels. The transport parameters are determined by resistivity measurements in the temperature range 4-300 K and magnetotransport in magnetic fields up to 12 T. The (subband) carrier concentrations and mobilities are extracted from the Hall data and Shubnikov-de Haas oscillations. We find that the transport parameters are strongly affected by the insertion of the AlAs central barrier. Photoluminescence spectra, measured at 77 K, show an increase of the transition energies upon insertion of the barrier. The transport and optical data are analyzed with help of self-consistent calculations of the subband structure and envelope wave functions. Insertion of the AlAs central barrier changes the spatial distribution of the electron wave functions and leads to the formation of hybrid states, i.e. states which extend over the InGaAs and the delta-doped layer quantum wells., 14 pages, pdf file more...
- Published
- 2007
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27. Transport and magnetic properties of Mn- and Mg-implanted GaAs layers
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P. V. Gurin, Polina M. Sheverdyaeva, R. A. Lunin, N. S. Perov, V. A. Kulbachinskii, and Yu. A. Danilov
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Ion implantation ,Materials science ,Magnetoresistance ,Condensed matter physics ,Ferromagnetism ,Hall effect ,Doping ,Analytical chemistry ,Supersaturated solid solution ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Abstract
Mn-doped GaAs layers were fabricated by direct ion implantation into semi-insulating GaAs (1 0 0) substrates. The implanted samples were annealed at temperatures T a = 700 – 800 ° C . At these temperatures MnAs clusters are formed in GaAs due to decay of the supersaturated solid solution of Mn in GaAs. Additional Mg ion implantation was used to provide an enhancement of p-type doping in (Ga,Mn)As layers. Temperature dependence of resistance was measured between 4.2 and 300 K, and the Hall effect was measured at temperatures of 4.2–200 K. Anomalous Hall effect and ferromagnetic behavior have been found for all samples. An enhanced positive magnetoresistance was also observed at T > 30 K . more...
- Published
- 2006
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28. Transport and magnetotransport properties of Mn-doped InxGa1−xAs/GaAs quantum well structures
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R. A. Lunin, O. V. Vikhrova, P. V. Gurin, B. N. Zvonkov, Yu. A. Danilov, V. A. Kulbachinskii, V. V. Rylkov, B. A. Aronzon, and A. B. Davydov
- Subjects
Physics ,X-ray absorption spectroscopy ,Condensed matter physics ,Magnetoresistance ,Quantum Hall effect ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Ferromagnetism ,Hall effect ,Condensed Matter::Strongly Correlated Electrons ,Mn doped ,Quantum well - Abstract
We report on the transport, magnetotransport and magnetic properties of In 0.17 Ga 0.83 As quantum well in GaAs δ-doped by Mn. At low temperatures, the anomalous Hall effect was observed which detects the spin-polarized carriers. Negative magnetoresistance was found at low temperatures, which became positive at high temperature. more...
- Published
- 2006
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29. Persistent IR photoconductivity in InAs/GaAs structures with QD layers
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B. N. Zvonkov, V. A. Casian, V. A. Rogozin, V. A. Kulbachinskiĭ, Vladimir G. Kytin, R. A. Lunin, and Z. M. Dashevsky
- Subjects
Materials science ,business.industry ,Photoconductivity ,Thermal ,Relaxation (NMR) ,Optoelectronics ,Logarithmic law ,Conductivity ,Condensed Matter Physics ,business ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Abstract
Persistent IR photoconductivity in InAs/GaAs structures with layers of QDs with a p-and n-type conductivity was studied. At the initial stage, after the illumination is switched off, the relaxation of photoconductivity follows a logarithmic law. The relaxation time depends on temperature; it decreases as temperature increases. A simple model of photoconductivity relaxation, based on thermal activation of carriers from the QD layer, is proposed. The model is consistent with the experimental data. more...
- Published
- 2006
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30. 2D metal slabs in new nickel–tin chalcogenides Ni7−δSnQ2 (QSe, Te): average crystal and electronic structures, chemical bonding and physical properties
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R. A. Lunin, A. I. Baranov, V.N. Nikiforov, Lars Kloo, V. A. Kulbachinskii, Anna Isaeva, and Boris A. Popovkin
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Chemistry ,Crystal structure ,Electronic structure ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Inorganic Chemistry ,Crystal ,Crystallography ,Tetragonal crystal system ,Chemical bond ,Materials Chemistry ,Ceramics and Composites ,Physical and Theoretical Chemistry ,Isostructural ,Electronic band structure ,Single crystal - Abstract
A systematic search for mixed low-valence, nickel–tin chalcogenides performed by establishing phase relations in the parts of Ni– Sn–Se and Ni–Sn–Te ternary systems resulted in the discovery of two new compounds, Ni5.62SnSe2 and Ni5.78SnTe2. Single crystals of both compounds were prepared by chemical transport with iodine and crystal structures were determined by single crystal X-ray investigation. The ED patterns for Ni5.78SnTe2 showed the presence of satellite reflections, which indicate a modulated structure with qE0:4a � : Average crystal structures of both compounds were determined to be of tetragonal symmetry (Sp.gr. I4=mmm; Z ¼ 2) with a ¼ 3:6890ð8Þ A ˚ , c ¼ 18:648ð3Þ A ˚ , Rw ¼ 0:0716 and a ¼ 3:7680ð5Þ A ˚ , c ¼ 19:419ð4Þ A ˚ , Rw ¼ 0:0832; correspondingly, and are isostructural to known Ni5.72SbSe2 and Ni5.66SbTe2. Measurements were carried out for both compounds with respect to thermal, electrical and magnetic properties. Ab initio band structure calculations were also performed to take a first glance into the electronic structure of such type compounds. The anisotropy of their band structure was found. Physical property measurements showed both compounds to be the anisotropic metallic conductors and paramagnetics. Calculated difference charge density maps revealed pairwise covalent and multicenter metallic nature of the d-metal—chalcogen and d-metal—p-metal interactions, respectively. more...
- Published
- 2004
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31. Fullerides: heterometallic superconductors with composition M2M′C60 (M = K, Rb; M′ = Yb, Lu, Sc)
- Author
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V. I. Privalov, Boris M. Bulychev, V. A. Kulbachinskii, R. A. Lunin, and Roman V. Shpanchenko
- Subjects
Ytterbium ,Superconductivity ,Lanthanide ,Crystallography ,chemistry ,Potassium ,Inorganic chemistry ,Anhydrous ,chemistry.chemical_element ,General Chemistry ,Scandium ,Lutetium ,Rubidium - Abstract
One- or two-step reactions of potassium and rubidium fullerides with composition MkC60 (M = K, Rb; k = 3—6) and K6C60 + m K mixtures (m = 1, 3) with anhydrous salts M′Cl3 (M′ = La, Pr, Nd, Sm, Gd, Tb, Yb, Lu, Y, Sc) and YbI2 in a toluene—THF medium afforded heterometallic fullerides M3–nM′nC60 (n = 1—3). Among these compounds, substituted fullerides with composition M2M′C60 (M′ = Yb, Lu, Sc) display superconducting properties with critical temperatures of 14—20 K. more...
- Published
- 2004
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32. Heterometallic fullerides of Fe and Cu groups with the composition K2MC60 (M=Fe+2, Fe+3, Co+2, Ni+2, Cu+1, Cu+2, Ag+1)
- Author
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K. Lips, Boris M. Bulychev, K. V. Poholok, A. V. Krechetov, Jörg Rappich, R. A. Lunin, V. A. Kulbachinskii, and Vladimir G. Kytin
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Mössbauer effect ,Condensed matter physics ,Chemistry ,General Chemistry ,Condensed Matter Physics ,Magnetic susceptibility ,Metal ,Magnetization ,Crystallography ,symbols.namesake ,Ferromagnetism ,visual_art ,Mössbauer spectroscopy ,symbols ,visual_art.visual_art_medium ,General Materials Science ,Qualitative inorganic analysis ,Raman spectroscopy - Abstract
Heterometallic fullerides with composition K 2 MC 60 , synthesized by exchange chemical reaction of K 5 C 60 or K 4 C 60 with chlorides of metals Fe and Cu groups have been investigated by X-ray diffraction, magnetic resonance, Raman and Mossbauer spectroscopy. Magnetization and susceptibility measurements have also been carried out. Metal chlorides from Fe and Cu groups enable to cover the whole range of electronic configuration of metal from d 5 to d 10 . Heterometallic fullerides with M=Cu +2 , Fe +2 , Fe +3 and Ni +2 appeared to be superconductors with T c =13.9–16.5 K. Ferromagnetism and superconductivity coexist in investigated fulleride K 2 Fe +3 C 60 . more...
- Published
- 2004
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33. New insights into the plateau-insulator transition in the quantum Hall regime
- Author
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L. A. Ponomarenko, A.M.M. Pruisken, A. de Visser, R. A. Lunin, B. N. Zvonkov, Duncan K. Maude, D.T.N. de Lang, Quantum Condensed Matter Theory (ITFA, IoP, FNWI), and Hard Condensed Matter (WZI, IoP, FNWI) more...
- Subjects
Physics ,Quantum phase transition ,Electron density ,Condensed matter physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,FOS: Physical sciences ,Quantum Hall effect ,Condensed Matter Physics ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Quantum spin Hall effect ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Quantum ,Critical exponent ,Quantum well - Abstract
We have measured the quantum critical behavior of the plateau-insulator (PI) transition in a low-mobility InGaAs/GaAs quantum well. The longitudinal resistivity measured for two different values of the electron density follows an exponential law, from which we extract critical exponents kappa = 0.54 and 0.58, in good agreement with the value (kappa = 0.57) previously obtained for an InGaAs/InP heterostructure. This provides evidence for a non-Fermi liquid critical exponent. By reversing the direction of the magnetic field we find that the averaged Hall resistance remains quantized at the plateau value h/e^2 through the PI transition. From the deviations of the Hall resistance from the quantized value, we obtain the corrections to scaling., Comment: accepted proceedings of EP2DS-15 (to be published in Physica E) more...
- Published
- 2004
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34. PECULIARITIES OF ELECTRON TRANSPORT IN THE COUPLED <font>AlGaAs</font>/<font>GaAs</font> QUANTUM WELLS WITH THIN CENTRAL <font>AlAs</font> BARRIER
- Author
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G. B. Galiev, R. A. Lunin, V. É. Kaminskii, I. S. Vasil’evskii, V. A. Kulbachinskii, and V. G. Mokerov
- Subjects
Electron mobility ,Materials science ,Condensed matter physics ,Quantum point contact ,Bioengineering ,Quantum Hall effect ,Condensed Matter Physics ,Electron transport chain ,Computer Science Applications ,Magnetic field ,General Materials Science ,Electrical and Electronic Engineering ,Wave function ,Quantum well ,Biotechnology ,Envelope (waves) - Abstract
GaAs / AlGaAs structures with single quantum well (QW) of different width and with coupled quantum wells separated by central barrier of six monolayers of AlAs have been synthesized by MBE. The temperature dependence of resistance, Hall electron concentration and mobility were investigated in the temperature interval 4.2 K more...
- Published
- 2003
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35. Persistent photoconductivity in quantum dot layers in InAs/GaAs structures
- Author
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P. V. Gurin, V. A. Kulbachinskii, V. A. Rogozin, Vladimir G. Kytin, R. A. Lunin, B. N. Zvonkov, and D. O. Filatov
- Subjects
Physics ,Condensed Matter::Materials Science ,Wavelength ,Condensed matter physics ,Quantum dot ,Doping ,Condensed Matter::Strongly Correlated Electrons ,Electron ,Quantum Hall effect ,Conductivity ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Variable-range hopping ,Magnetic field - Abstract
We synthesized InAs/GaAs structures with quantum dot layers and investigated electron (Si doping) lateral transport in the temperature interval 0.05 K < T < 300 K in the dark and under illumination by light over a wide interval of wavelengths in magnetic fields up to 6 T. All the samples exhibited a positive persistent photoconductivity at T < 250 K. Without illumination in the high carrier density samples the Shubnikov–de Haas effect and the quantum Hall effect were observed. Low carrier density samples showed a 2D Mott variable range hopping conductivity. The morphology of the quantum dot layers was investigated by atomic force microscopy (AFM). The length of localization exceeds the average quantum dot size and correlates very well with the quantum dot cluster size obtained by AFM. more...
- Published
- 2003
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36. Lateral electronic transport in short period InAs/GaAs superlattices at the threshold of quantum dot formation
- Author
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E. Narumi, K. Kindo, A. de Visser, V. G. Mokerov, Yu.V. Khabarov, Yu.V. Federov, R. A. Lunin, V. A. Rogozin, V. A. Kulbachinskii, and Hard Condensed Matter (WZI, IoP, FNWI)
- Subjects
Photoluminescence ,Materials science ,Condensed matter physics ,Quantum dot ,Superlattice ,Monolayer ,Electron ,Conductivity ,Condensed Matter Physics ,Anisotropy ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Magnetic field - Abstract
Temperature dependences of resistance at 0.7 K
- Published
- 2003
37. Quantum oscillations of Hall resistance, magnetoresistance in a magnetic field up to 54 T and the energy spectrum of Sn doped layered semiconductors p-(Bi1 xSbx)2Te3
- Author
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R. A. Lunin, Yasuo Narumi, Ken-ichi Suga, Petr Lostak, V. A. Kulbachinskii, K. Kindo, Shinji Kawasaki, N. Miyajima, Misao Sasaki, A. Yu. Kaminsky, and P. Hajek
- Subjects
Condensed matter physics ,Magnetoresistance ,Band gap ,Chemistry ,Quantum oscillations ,Landau quantization ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Semimetal ,Electronic, Optical and Magnetic Materials ,Effective mass (solid-state physics) ,Hall effect ,Materials Chemistry ,Condensed Matter::Strongly Correlated Electrons ,Electrical and Electronic Engineering ,Quasi Fermi level - Abstract
The Hall effect and the Shubnikov–de Haas (SdH) effect have been investigated in magnetic fields up to 54 T in p-(Bi1−xSbx)2Te3 (0 ≤ x ≤ 1.0) Sn doped single crystals. Doping of (Bi1−xSbx)2Te3 with tin has shown that Sn exhibits acceptor properties in all crystals. We discuss the valence band structure of (Bi1−xSbx)2Te3 with the upper valence band (light hole band (LHB)), the lower valence band (heavy hole band (HHB)) and Sn-induced impurity band (IB). The Hall resistivity ρH as a function of magnetic field shows quantization in the form of plateaus. The calculated Landau levels of the LHB with the best-fit parameters are in agreement with the experiment. The oscillation of ρH is due to the presence of the carrier reservoir. The impurity resonant band with a high density of states or the HHB with a higher hole effective mass serve as the reservoir. more...
- Published
- 2002
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38. Optical and transport properties of short period InAs/GaAs superlattices near quantum dot formation
- Author
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Yu. V. Fedorov, R. A. Lunin, A. de Visser, Yu. V. Khabarov, V. A. Rogozin, V. A. Kulbachinskii, V. G. Mokerov, and WZI (IoP, FNWI)
- Subjects
Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Period (periodic table) ,Condensed matter physics ,Superlattice ,FOS: Physical sciences ,Conductivity ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Variable-range hopping ,Electronic, Optical and Magnetic Materials ,Metal ,Condensed Matter::Materials Science ,Quantum dot ,visual_art ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Materials Chemistry ,visual_art.visual_art_medium ,Electrical and Electronic Engineering - Abstract
We have investigated the optical and transport properties of MBE grown short-period superlattices of InAs/GaAs with different numbers of periods (3 = 2.7 ML quantum dots are formed and the metallic type of conductivity changes to variable range hopping conductivity., 15 pages (incl.7 figures); pdf file; submitted to Semicond. Sci. Technol more...
- Published
- 2002
39. Electrical transport and persistent photoconductivity in quantum dot layers in InAs/GaAs structures
- Author
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R. A. Lunin, B. N. Zvonkov, Vladimir G. Kytin, V. A. Kulbachinskii, A. V. Demin, V. A. Rogozin, A. V. Golikov, S. M. Nekorkin, and D. O. Filatov
- Subjects
Materials science ,Photoluminescence ,Condensed matter physics ,Solid-state physics ,Quantum dot ,Density of states ,General Physics and Astronomy ,Atmospheric temperature range ,Conductivity ,Spectroscopy ,Magnetic field - Abstract
The conductivity of quantum dot layers is studied in InAs/GaAs structures in the temperature range from 300 to 0.05 K in the dark and using two types of illumination in magnetic fields up to 6 T. Depending on the initial concentration of current carriers, the conductivity of the structures varied from metallic (the Shubnikov-de Haas effect was observed) to hopping conductivity. At low temperatures, the temperature dependence of the resistance changed from the Mott dependence to the dependence described by the Shklovskii-Efros law for hopping conductivity in the presence of the Coulomb gap in the density of states. The conductivity of samples was studied upon their illumination at λ = 791 nm and λ > 1120 nm. All the samples exhibited a positive persistent photoconductivity at T < 250 K. The structures were also studied using photoluminescence and an atomic force microscope. more...
- Published
- 2001
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40. Wavelength dependent negative and positive persistent photoconductivity in Sn δ-doped GaAs structures
- Author
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A. de Visser, A. V. Golikov, V. A. Kulbachinskii, A.S. Bugaev, A.P. Senichkin, Vladimir G. Kytin, R.T.F. van Schaijk, R. A. Lunin, and WZI (IoP, FNWI)
- Subjects
Condensed Matter - Materials Science ,Materials science ,Magnetoresistance ,Band gap ,Photoconductivity ,Doping ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Electron ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Wavelength ,Hall effect ,Materials Chemistry ,Electrical and Electronic Engineering ,Atomic physics ,Excitation - Abstract
The photoconductivity of GaAs structures delta-doped by Sn has been investigated for wavelengths lambda= 650-1200 nm in the temperature interval T= 4.2-300 K. The electron densities and mobilities, before and after illumination, have been determined by magnetoresistance, Shubnikov-de Haas effect and Hall effect measurements, in high magnetic fields. For the heavily doped structures (n_H> 2x10^13 cm^-2) we observe under illumination by light with wavelengths larger than the band-gap wavelength of the host material (lambda= 815 nm at T= 4.2 K) first positive (PPPC) and then negative (NPPC) persistent photoconductivity. The NPPC is attributed to the ionisation of DX centres and PPPC is explained by the excitation of electrons from Cr impurity states in the substrate. For lambda< 815 nm in addition the excitation of electron over the band gap of GaAs contributes to the PPPC. For the lightly doped structures (n_H, 17 pages (includes 6 figures); Postscript file; Semicond. Sci. Technol. in print more...
- Published
- 2000
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41. Negative persistent photoconductivity in GaAs (δ-Sn) structures
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R. A. Lunin, A.S. Bugaev, A. V. Demin, Vladimir G. Kytin, A. V. Golikov, A. de Visser, A.P. Senichkin, R.T.F. van Schaijk, and V. A. Kulbachinskii
- Subjects
Electron mobility ,Electron density ,Materials science ,chemistry ,Condensed matter physics ,Ionization ,Photoconductivity ,Doping ,General Physics and Astronomy ,chemistry.chemical_element ,Atmospheric temperature range ,Tin ,Vicinal - Abstract
The effect of illumination with various wavelengths λ (770 nm
- Published
- 1999
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42. Peculiarities of optical and low-temperature transport properties of multi-layer InAs/GaAs structures with quantum dots
- Author
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Yu. N. Saf'yanov, Vladimir G. Kytin, A. V. Golikov, V. A. Kulbachinskii, R. A. Lunin, I. G. Malkina, and B. N. Zvonkov
- Subjects
Photoluminescence ,Materials science ,Condensed matter physics ,Condensed Matter::Other ,Electron ,Atmospheric temperature range ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Shubnikov–de Haas effect ,Electron localization function ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Quantum dot ,Electrical and Electronic Engineering ,Anisotropy ,Vicinal - Abstract
Transport properties and photoluminescence of InAs/GaAs structures with quantum dots on vicinal surfaces have been investigated as a function of InAs content. It was found that quantum dots form 2D hole or electron layers, for which Shubnikov–de Haas effect can be observed. The temperature dependence of the resistance was measured in the [1 1 0] and [−1 1 0] directions in the temperature range 4.2–300 K and revealed an anisotropy of conductivity. Strong localization occurs with decreasing temperature when electrons become trapped in the random potential. more...
- Published
- 1999
- Full Text
- View/download PDF
43. Transport and optical properties of tin-delta-doped GaAs structures
- Author
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Vladimir G. Kytin, A. V. Perestoronin, A.S. Bugaev, A. de Visser, V. A. Kulbachinskii, A. L. Karuzskii, R.T.F. van Schaijk, V. G. Mokerov, R. A. Lunin, A.P. Senichkin, and WZI (IoP, FNWI)
- Subjects
Photoluminescence ,Condensed matter physics ,Chemistry ,Fermi level ,Doping ,chemistry.chemical_element ,Atmospheric temperature range ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Magnetic field ,symbols.namesake ,Atomic electron transition ,symbols ,Density of states ,Tin - Abstract
The transport and optical properties of tin δ layers in GaAs are investigated as functions of the Sn concentration. The Shubnikov-de Haas and Hall effects are measured in the temperature range 0.4–12 K in magnetic fields up to 38 T. The band diagrams and quantum mobilities of electrons in the quantum-well subbands are calculated. Features associated with electronic transitions from quantum-well levels are found in the photoluminescence spectra of the structures. Oscillations of the resistance are observed in a magnetic field parallel to the δ layer and are attributed to features in the density of states at the Fermi level. more...
- Published
- 1999
44. Influence of state hybridization on low-temperature electron transport in shallow quantum wells
- Author
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R. A. Lunin, V. G. Mokerov, G. B. Galiev, I. S. Vasil’evskii, and V. A. Kulbachinskiĭ
- Subjects
Electron mobility ,Materials science ,Condensed matter physics ,Solid-state physics ,Condensed Matter::Other ,Scattering ,Doping ,General Physics and Astronomy ,Electron ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter::Materials Science ,Electron diffraction ,Electronic band structure ,Quantum well - Abstract
We investigate the lateral low-temperature electron transport in shallow pseudomorphous two-sided δ-doped GaAs/In0.12Ga0.88As/GaAs quantum wells (QWs) depending on the QW width, doping level, and the presence of a thin central AlAs barrier. Such a barrier is shown to change the band structure and wave functions of electrons in the QWs, causing a significant change in the scattering of electrons and a change in their mobility. more...
- Published
- 2007
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- View/download PDF
45. Superconductivity and spectroscopy of heterofullerides Rb2MC60, K2MC60, and KM2C60 (M = Mg, Be)
- Author
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R. A. Lunin, Elizaveta A. Konstantinova, V. A. Kulbachinskiĭ, A. V. Krechetov, Vladimir G. Kytin, and Boris M. Bulychev
- Subjects
Superconductivity ,Paramagnetism ,Materials science ,Condensed matter physics ,Magnetism ,law ,General Physics and Astronomy ,Resonance ,Electron ,Spectroscopy ,Electron paramagnetic resonance ,Magnetic susceptibility ,law.invention - Abstract
A series of new heterofullerides with compositions Rb2MC60, K2MC60, and KM2C60 (M = Mg, Be) have been synthesized. Measurements of the temperature dependences of the magnetic susceptibility in the temperature interval from 4.2 to 300 K reveal a superconducting transition in heterofullerides K2MgC60, KMg2C60, K2BeC60, and Rb2BeC60 at temperatures Tc = 13–22 K. The electron states with uncompensated spin are studied by the electron paramagnetic resonance technique. The contributions of conduction electrons and localized electrons to the paramagnetic susceptibility are extracted. more...
- Published
- 2007
- Full Text
- View/download PDF
46. Magnetotransport in GaAs δ-doped by Sn
- Author
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R.T.F. van Schaijk, A.S. Bugaev, V. A. Kulbachinskii, R. A. Lunin, V. G. Mokerov, Vladimir G. Kytin, A. de Visser, and A.P. Senichkin
- Subjects
Electron density ,Dense array ,Materials science ,Condensed matter physics ,Magnetoresistance ,Scattering ,Doping ,Step edges ,Electrical and Electronic Engineering ,Condensed Matter Physics ,Anisotropy ,Vicinal ,Electronic, Optical and Magnetic Materials - Abstract
We have investigated the magnetotransport properties of vicinal (0 0 1) GaAs structures misoriented by 3° towards the (1 1 0) direction. The structures are δ-doped with Sn which predominantly accumulates at the step edges. In this way a dense array of 1D channels ( d =54 A) is formed. Shubnikov–de Haas oscillations show the presence of several subbands. A clear anisotropy in the electronic parameters is observed for a current ‖ and ⊥ to the step edges, notably R ⊥ / R ‖ ∼1.5 (at T =4.2 K) for a sample with an electron density n Hall =8 × 10 12 cm −2 . We have also found a significant anisotropy in n Hall , μ Hall and n SdH . The difference in n Hall and μ Hall could be explained by preferential scattering in one direction, caused by a preferential attachment of the Sn atoms on the step edges. For the difference in n SdH there is no clear explanation. more...
- Published
- 1998
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47. Conducting wires embedded in an i-GaAs matrix for electronic applications
- Author
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V. A. Kulbachinskii, A. V. Demin, A.S. Bugaev, R. A. Lunin, A.P. Senichkin, and Vladimir G. Kytin
- Subjects
business.industry ,Chemistry ,Plane (geometry) ,Quantum wire ,chemistry.chemical_element ,Nanotechnology ,Substrate (electronics) ,Atmospheric temperature range ,Condensed Matter Physics ,Epitaxy ,Atomic and Molecular Physics, and Optics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Electric field ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Tin ,Vicinal - Abstract
A method of fabricating quasi-1D conducting wires of tin embedded in an i -GaAs matrix has been developed. The method involves forming a system of steps on vicinal surface of the GaAs(Cr) substrate misoriented 0.3° or 1° from the (001) plane forward to the (110) basal plane and decorating the ends of these steps with Sn through molecular-beam epitaxy. Transport properties of structures were measured in the temperature range 4.2–300 K at high electric fields up to E= 10 4 V/cm using a pulse technique. more...
- Published
- 1998
- Full Text
- View/download PDF
48. Low temperature transport properties of InAs/GaAs structures with quantum dots
- Author
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V. A. Kulbachinskii, R. A. Lunin, B. N. Zvonkov, I. G. Malkina, Yu. N. Saf'yanov, and Vladimir G. Kytin
- Subjects
Photoluminescence ,Condensed matter physics ,Magnetoresistance ,Chemistry ,Atmospheric temperature range ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Shubnikov–de Haas effect ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Hall effect ,Quantum dot ,Electrical and Electronic Engineering ,Anisotropy - Abstract
The transport and optical properties of InAs/GaAs structures with quantum dots have been investigated as a function of InAs content. Photoluminescence (PL) spectra showed polarization of radiation in the plane of the structures. The temperature dependence of the resistance was measured in the [110] and [−110] directions in the temperature range 4.2 K–300 K and anisotropy of conductivity was found. The Shubnikov de Haas effect, magnetoresistance ρ ( B ) and the Hall effect have been measured in a magnetic field B up to 10 T. more...
- Published
- 1998
- Full Text
- View/download PDF
49. Galvanomagnetic properties of Hg1−x MnxTe1−y Sey semimagnetic semiconductors
- Author
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R. A. Lunin, V. A. Kulbachinskii, P.D. Maryanchuk, and I. A. Churilov
- Subjects
Materials science ,Semiconductor ,Condensed matter physics ,Solid-state physics ,Magnetoresistance ,Hall effect ,business.industry ,General Physics and Astronomy ,Electron ,Atmospheric temperature range ,Conductivity ,business ,Magnetic field - Abstract
The galvanomagnetic properties of single crystals of the semimagnetic semiconductors Hg1−xMnxTe1−ySey with 0.01
- Published
- 1997
- Full Text
- View/download PDF
50. Quenching of persistent photoconductivity and decrease of electron concentration by high electric fields in GaAs delta-doped by Sn on vicinal substrate structures
- Author
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Vladimir G. Kytin, E. V. Bogdanov, A.P. Senichkin, V. A. Kulbachinskii, and R. A. Lunin
- Subjects
Quenching ,Materials science ,Condensed matter physics ,Photoconductivity ,Doping ,Substrate (electronics) ,Atmospheric temperature range ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Electric field ,Electrical and Electronic Engineering ,Current density ,Vicinal - Abstract
This paper reports the measurements of high electric field transport and the persistent photoconductivity in delta-doped by Sn on vicinal and singular substrate GaAs structures. Transport properties of the hot electron gas were measured in the temperature range 4.2 K more...
- Published
- 1997
- Full Text
- View/download PDF
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