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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Borisov A. A., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Doping dependence of the band structure and chemical potential in cuprates by the generalized tight-binding method
Коллективы : International Conference on Modern Problems in Superconductivity
Место публикации : Mod. Phys. Lett. B/ International Conference on Modern Problems in Superconductivity (3 ; 2002 ; Sept. ; 9-14 ; Yalta, Ukrain). - 2003. - Vol. 17, Is. 10-12. - P.479-486. - ISSN 0217-9849, DOI 10.1142/S0217984903005500
Примечания : Cited References: 12
Предметные рубрики: CORRELATED ELECTRONS
SUPERCONDUCTIVITY
OXIDES
Аннотация: Quasiparticle band structure in hole doped CuO2 layer is calculated with account for strong electron correlations in the framework of multiband p-d model. For undoped layer we obtain the charge-transfer antiferromagnetic insulator. With doping unusual impurity-like quasiparticle appears at the top of the valence band with spectral weight proportional to doping concentration. In the overdoped regime the band structure in the paramagnetic phase results in the doping dependent Fermi surface in agreement to ARPES data.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Borisov A.A., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Temperature and concentration dependences of the electronic structure of copper oxides in the generalized tight binding method
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 97, Is. 4. - P773-780. - ISSN 1063-7761, DOI 10.1134/1.1625067
Примечания : Cited References: 25
Предметные рубрики: SUPERCONDUCTING-GAP ANISOTROPY
BAND-STRUCTURE
FERMI-SURFACE
NORMAL-STATE
BI2SR2CACU2O8+DELTA
EVOLUTION
Ключевые слова (''Своб.индексиров.''): doping (additives)--electron transitions--electronic structure--fermi level--fermi surface--electron correlations--pseudogap--tight binding method--valence band--copper oxides
Аннотация: The electronic structure of p-type doped HTSC cuprates is calculated by explicitly taking into account strong electron correlations. The smooth evolution of the electronic structure from undoped antiferromagnetic to optimally and heavily doped paramagnetic compositions is traced. For a low doping level, in-gap impurity-type states are obtained, at which the Fermi level is pinned in the low-doping region. These states are separated by a pseudogap from the valence band. The Fermi surfaces calculated for the paramagnetic phase for various concentrations of holes are in good agreement with the results of ARPES experiments and indicate a gradual change in the Fermi surface from the hole type to the electron type. (C) 2003 MAIK "Nauka/Interperiodica".
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivantsov I. D., Ferraz A., Kochetov E.
Заглавие : Breakdown of the Nagaoka phase at finite doping
Место публикации : Phys. Rev. B: American Physical Society, 2017. - Vol. 95, Is. 15. - Ст.155115. - ISSN 10980121 (ISSN), DOI 10.1103/PhysRevB.95.155115
Примечания : Cited References: 39
Аннотация: The Nagaoka (U=∞) limit of the Hubbard model on a square lattice is mapped onto the itinerant-localized Kondo model at infinitely strong coupling. Such a model is well suited to perform quantum Monte Carlo (QMC) simulations to compute spin correlation functions. For periodic boundary conditions, this model is shown to exhibit no short-range ferromagnetic (FM) spin correlations at any doping δ≥0.01 and at finite temperature T=0.1t. Our simulations give no indication that there is a tendency towards ferromagnetic ordering in the ground state, with more than one hole. Employing on the other hand the open boundary conditions (or mixed boundary conditions) may result in the qualitatively different results for the thermodynamic limit depending on the way one chooses to approach this limit. These observations imply that the relevant thermodynamic limit remains unclear.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu Q., Dang P., Zhang G., Lian H., Li G., Molokeev M. S., Cheng Z., Lin J.
Заглавие : Broad luminescence tuning in Mn2+-doped Rb2Zn3(P2O7)2 via doping level control based on multiple synergies
Место публикации : CrystEngComm. - 2022. - Vol. 24, Is. 31. - P.5622-5629. - ISSN 14668033 (ISSN), DOI 10.1039/d2ce00719c
Примечания : Cited References: 31. - We acknowledge the financial support from the National Natural Science Foundation of China (NSFC No. 51932009, 51720105015, 51929201, 52072349, and 52172166), Projects for the Science and Technology Development Plan of Jilin Province (20210402046GH), and the Natural Science Foundation of Zhejiang Province (LR22E020004)
Аннотация: Here we constructed a series of novel non-centrosymmetric structure phosphors [Rb2Zn3(P2O7)2:Mn2+] by a high-temperature solid-state reaction. The multiband emission can be designed by Mn2+ preferentially occupying three types of crystallographic sites in Rb2Zn3(P2O7)2:Mn2+. The emission color could be continuously tuned from yellow-green to orange-red via multiple synergies among crystallographic site engineering, energy transfer, and Mn-Mn dimmers alone through the dopant concentration. These color-tunable phosphors have good thermal stability (I150 °C/I25 °C = 91%). The as-prepared pc-WLED has a low corresponding color temperature (CCT = 4820 K) and a high color rendering index (Ra = 90.4) with CIE color coordinates of (0.351, 0.358). These results show that emission-tunable Rb2Zn3(P2O7)2:xMn2+ phosphors are potential candidates for application in n-UV-based pc-WLED devices. This study offers a new insight for wide-range tuning of PL properties by using crystallographic site engineering through changing the doping level in Mn-activated phosphors.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhou, Guojun, Ding, Jialiang, Jiang, Xingxing, Zhang, Jian, Molokeev M. S., Ren, Qiqiong, Zhou, Jun, Li, Shili, Zhang, Xian-Ming
Заглавие : Coordination units of Mn2+ modulation toward tunable emission in zero-dimensional bromides for white light-emitting diodes
Место публикации : J. Mater. Chem. C. - 2022. - Vol. 10, Is. 6. - P.2095-2102. - ISSN 2050-7526, DOI 10.1039/d1tc05680h. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 57. - The present work was supported by the Natural Science Foundation of China (21871167), the 1331 Project of Shanxi Province and the Postgraduate Innovation Project of Shanxi Normal University (2019XBY018), the Beijing Natural Science Foundation (No. 2214068) and funded by RFBR according to the research project no. 19-52-80003
Предметные рубрики: HALIDE PEROVSKITE NANOCRYSTALS
RECENT PROGRESS
DOPING MN2+
Аннотация: Organic–inorganic metal halides have become a multifunctional platform for manipulating photoluminescence due to highly efficient and tunable emissions, especially for lead-free Mn2+-based halides. Herein, the zero-dimensional (0D) bromides of (C5H14N3)2MnBr4 and (CH6N3)2MnBr4 with different coordination environments were designed and synthesized by a solvent evaporation method. They exhibit green and red broadband emission peaks at 528 nm and 627 nm with high photoluminescence quantum yields of 86.83% and 61.91%, respectively, which are attributed to the d–d transition (4T1(G) → 6A1(S)) of [MnBr4]2− tetrahedral and [Mn3Br12]6− octahedral units. The cases emphasize the effect of organic ligands on the intrinsic emissions of Mn2+ ions, thereby revealing the luminescence mechanism of Mn2+ ions in 0D isolated structures through the Tanabe–Sugano (TS) energy diagram. Thanks to their bright and stable emissions, the fabricated white light-emitting diode (LED) based on (C5H14N3)2MnBr4 and (CH6N3)2MnBr4 provides an outstanding color rendering index (Ra) of 90.8 at a correlated color temperature (CCT) of 3709 K, along with the CIE chromaticity coordinates of (0.3985, 0.3979) and a luminous efficacy of 51.2 lm W−1. This work aims at clarifying the relationship between the coordination units of Mn2+ and tunable emissions, and in particular, proposes a new strategy to explore phosphors excited by blue light for white LEDs.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Gavrichkov V. A., Ovchinnikov S. G., Nekrasov I. A., Kokorina E. E., Pchelkina Z. V.
Заглавие : Dominance of many-body effects over the one-electron mechanism for band structure doping dependence in Nd2-xCexCuO4: the LDA + GTB approach
Разночтения заглавия :авие SCOPUS: Dominance of many-body effects over the one-electron mechanism for band structure doping dependence in Nd2-xCexCuO4: The LDA+GTB approach
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2007. - Vol. 19, Is. 48. - Ст.486203. - ISSN 0953-8984, DOI 10.1088/0953-8984/19/48/486203
Примечания : Cited References: 36
Предметные рубрики: NARROW ENERGY BANDS
HUBBARD-MODEL
SUPERCONDUCTORS
DENSITY
TEMPERATURE
ORBITALS
WAVE
Ключевые слова (''Своб.индексиров.''): antiferromagnetism--band structure--correlation methods--crystal structure--local density approximation--superconducting materials--electronic correlations--fermionic quasiparticles--neodymium compounds
Аннотация: In the present work we report band structure calculations for the high-temperature superconductor Nd2-xCexCuO4 in the regime of strong electronic correlations within an LDA + GTB method, which combines the local density approximation (LDA) and the generalized tight-binding method (GTB). The two mechanisms of band structure doping dependence were taken into account. Namely, the one-electron mechanism provided by the doping dependence of the crystal structure, and the many-body mechanism provided by the strong renormalization of the fermionic quasiparticles due to the large on-site Coulomb repulsion. We have shown that, in the antiferromagnetic and in the strongly correlated paramagnetic phases of the underdoped cuprates, the main contribution to the doping evolution of the band structure and Fermi surface comes from the many-body mechanism.
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7.

Вид документа : Статья из журнала (Препринт)
Шифр издания :
Автор(ы) : Kuz'min V. I., Visotin M. A., Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Doping and temperature evolution of pseudogap and spin-spin correlations in the two-dimensional Hubbard model [Electronic resource]
Место публикации : ArXiv. - 2020. - Ст.2001.05143
Вид и объем ресурса: Electronic text data
Примечания : Cited References: 86. - The reported study was funded by RFBR according to the research project No. 18-32-00256 (all the results concerning the influence of short-range correlations on the electronic spectral properties). The reported study was also funded by Russian Foundation for Basic Research and Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects “Electronic correlation effects and multiorbital physics in iron-based materials and cuprates” number 19-42-240007, and “Features of electron-phonon coupling in high-temperature superconductors with strong electron correlations” number 18-42-240017
Предметные рубрики: Strongly Correlated Electrons
Аннотация: Cluster perturbation theory is applied to the two-dimensional Hubbard t−t′−t′′−U model to obtain doping and temperature dependent electronic spectral function with 4×4 and 12-site clusters. It is shown that evolution of the pseudogap and electronic dispersion with doping and temperature is similar and in both cases it is significantly influenced by spin-spin short-range correlations. When short-range magnetic order is weakened by doping or temperature and Hubbard-I like electronic dispersion becomes more pronounced, the Fermi arc turns into large Fermi surface and the pseudogap closes. It is demonstrated how static spin correlations impact the overall dispersion's shape and how accounting for dynamic contributions leads to momentum-dependent spectral weight at the Fermi surface and broadening effects.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min V. I., Visotin M. A., Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Doping and temperature evolution of pseudogap and spin-spin correlations in the two-dimensional Hubbard model
Коллективы : RFBRRussian Foundation for Basic Research (RFBR) [18-32-00256, 18-32-01062]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR); Government of Krasnoyarsk Territory; Krasnoyarsk Regional Fund of Science [19-42-240007, 18-42-240017]
Место публикации : Phys. Rev. B. - 2020. - Vol. 101, Is. 11. - Ст.115141. - ISSN 2469-9950, DOI 10.1103/PhysRevB.101.115141. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 97. - The reported study was funded by RFBR according to Research Project No. 18-32-00256 (all the results concerning the influence of short-range correlations on the electronic spectral properties). The reported study was also funded by RFBR according to Research Project No. 18-32-01062; the Russian Foundation for Basic Research and Government of Krasnoyarsk Territory, the Krasnoyarsk Regional Fund of Science to the Research Projects "Electronic correlation effects and multiorbital physics in iron-based materials and cuprates" No. 19-42-240007 and "Features of electron-phonon coupling in high-temperature superconductors with strong electron correlations" No. 18-42-240017.
Предметные рубрики: QUASI-PARTICLE DISPERSION
FERMI-SURFACE
QUANTUM OSCILLATIONS
LANCZOS METHOD
Аннотация: Cluster perturbation theory is applied to the two-dimensional Hubbard t - t' - t '' - U model to obtain doping and temperature-dependent electronic spectral function with 4 x 4 and 12-site clusters. It is shown that evolution of the pseudogap and electronic dispersion with doping and temperature is similar and in both cases it is significantly influenced by spin-spin short-range correlations. When short-range magnetic order is weakened by doping or temperature and Hubbard-I-like electronic dispersion becomes more pronounced, the Fermi arc turns into a large Fermi surface and the pseudogap closes. It is demonstrated how static spin correlations impact the overall dispersion's shape and how accounting for dynamic contributions leads to momentum-dependent spectral weight at the Fermi surface and broadening effects.
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9.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Patrin G.S., Yurkin G.Yu., Beletsky V.V., Volkov N.V., Velikanov D.A.
Заглавие : Doping dependence of magnetic and electrical properties in Fe1-xCoxSi
Коллективы : Institute of Physics, Joint European Magnetic Symposia
Место публикации : 5th Joint Europ. Magn. Symp. (JEMS-2010): Book of abstracts. - 2010. - С. 153
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneyder E. I., Korshunov M. M., Makarov I. A.
Заглавие : Doping dependent band structure and pairing in strongly correlated electron systems of high-Tc cuprates
Коллективы : International symposium on strong nonlinear vibronic and electronic interactions in solids
Место публикации : V International symposium on strong nonlinear vibronic and electronic interactions in solids: program, book of abstracts . - 2015. - Ст.O18. - P.28
Примечания : Библиогр.: 1 назв.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bhalla N., Taneja S., Thakur P., Sharma P. K., Mariotti D., Maddi C., Ivanova O. S., Petrov D. A., Sukhachev A. L., Edelman I. S., Thakur A.
Заглавие : Doping independent work function and stable band gap of spinel ferrites with tunable plasmonic and magnetic properties
Место публикации : Nano Lett. - 2021. - Vol. 21, Is. 22. - P.9780-9788. - ISSN 15306984 (ISSN), DOI 10.1021/acs.nanolett.1c03767
Примечания : Cited References: 41. - All authors would like to acknowledge support from EPSRC fund, award no. EP/R008841/1. Nikhil Bhalla wishes to thank Department of Economy, Northern Ireland, for supporting part of this work under GCRF Pump Priming Fund. Additionally, Atul Thakur and Preeti Thakur would like to acknowledge Gurujal, an initiative with district administration Gurugram for financial assistance from project no.176, Amity Incubation grant from the Ministry of Electronics and Information Technology (MeitY) under Technology Incubation and Development of Entrepreneurs (TIDE 2.0) program and the startup nanoLatticeX
Аннотация: Tuning optical or magnetic properties of nanoparticles, by addition of impurities, for specific applications is usually achieved at the cost of band gap and work function reduction. Additionally, conventional strategies to develop nanoparticles with a large band gap also encounter problems of phase separation and poor crystallinity at high alloying degree. Addressing the aforementioned trade-offs, here we report Ni–Zn nanoferrites with energy band gap (Eg) of ≈3.20 eV and a work function of ≈5.88 eV. While changes in the magnetoplasmonic properties of the Ni–Zn ferrite were successfully achieved with the incorporation of bismuth ions at different concentrations, there was no alteration of the band gap and work function in the developed Ni–Zn ferrite. This suggests that with the addition of minute impurities to ferrites, independent of their changes in the band gap and work function, one can tune their magnetic and optical properties, which is desired in a wide range of applications such as nanobiosensing, nanoparticle based catalysis, and renewable energy generation using nanotechnology.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G.
Заглавие : Doping-dependent evolution of low-energy excitations and quantum phase transitions within an effective model for high-Tc copper oxides
Место публикации : The European Physical Journal B - Condensed Matter and Complex Systems: Springer-Verlag GmbH, 2007. - Т. 57, № 3. - С. 271-278. - ISSN 1434-6028, DOI 10.1140/epjb/e2007-00179-2. - ISSN 1434-6036(eissn)
ГРНТИ : 29.19
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G.
Заглавие : Doping-dependent evolution of low-energy excitations and quantum phase transitions within an effective model for high-Tc copper oxides
Место публикации : The European Physical Journal B - Condensed Matter and Complex Systems: Springer-Verlag GmbH, 2007. - Т. 57, № 3. - С. 271-278. - ISSN 1434-6028, DOI 10.1140/epjb/e2007-00179-2. - ISSN 1434-6036(eissn)
ГРНТИ : 29.19
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Draganyuk O. N., Zamkova N. G., Zhandun V. S.
Заглавие : Effect of substitution of Mn and Ga atoms by Fe atom in the Mn2GaC MAX phase
Место публикации : J. Magn. Magn. Mater. - 2022. - Vol. 563. - Ст.169860. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2022.169860
Примечания : Cited References: 40. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project № 20-42-240004: “The effect of the composition, pressure, and dimension on the magnetic, electronic, optical, and elastic properties of the magnetic M n+1 AX n (M = Cr, Mn; Fe, A = Al, Ga, Si, Ge, P, In; X = C, N; n = 1-3) MAX-phases”. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” ( http://ckp.urcki.ru ). The ternary phase diagrams for the calculation of formation enthalpies were taken from Materials Project ( https://materialsproject.org ) and OQMD ( https://oqmd.org/ ) databases
Аннотация: The magnetic properties of ordered and disordered MAX-phase Mn2-xFe2xGaC and Mn2Ga1-xFexC (x = 12.5, 25, and 50 at.%) have been studied within DFT-GGA. The investigation of phase stability of M2AX phases is performed by comparing the total energy of MAX phases to that of the set of competitive phases for calculation of the phase formation enthalpy. At the small concentration of Fe atoms (x = 12.5 %) compound remains stable. We have found that introducing Fe atom at A-site leads to the forming of ferromagnetic phase with large magnetic moments on magnetic atoms and magnetization. Through detailed group-theoretical analysis we have obtained that only ferromagnetic ordering is possible when Fe atom ordering over Ga sites. The study of exchange constants shows that the out-of-plane Fe-Mn exchange gives the main contribution in appearance of ferromagnetic phase. The temperature dependences of magnetization reveal the increase of Curie temperature in Mn2GaC with Fe atom incorporated into Ga-site.
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15.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Udod L. V., Aplesnin S. S., Eremin E. V., Sitnikov M. N., Molokeev M. S.
Заглавие : Effect of Mn doping on magnetic and dielectric properties of Bi2Sn2O7
Коллективы : Moscow International Symposium on Magnetism
Место публикации : Moscow Int. Symp. on Magnet. (MISM-2014): Book of abstracts. - 2014. - Ст.1PO-J1-6. - P.513. - ISBN 978-5-91978-025-0
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Udod L. V., Aplesnin S. S., Sitnikov M. N., Eremin E. V., Molokeev M. S.
Заглавие : Effect of Mn doping on magnetic and dielectric properties of Bi2Sn2O7
Коллективы : Moscow International Symposium on Magnetism
Место публикации : Solid State Phenom.: Selected, peer reviewed papers/ ed.: N. Perov, A. Semisalova: Trans Tech Publications Ltd, 2015. - Vol. 233-234: Achievements in Magnetism. - P.105-108. - ISSN 1662-9779, DOI 10.4028/www.scientific.net/SSP.233-234.105. - ISSN 978-3-03835-482-6
Предметные рубрики: Achievements in magnetism
Ключевые слова (''Своб.индексиров.''): crystallographic structure--cubic phase--dielectric permeability--electrical resistivity--magnetic moment--martensitic phase transitions--orthorhombic phases--polymorphic transformation
Аннотация: The Bi2(Sn0.95Mn0.05)2O7 compound existing simultaneously in two polymorphic modifications, namely, orthorhombic and cubic has been synthesized for the first time by solid-phase synthesis. The magnetic, dielectric and electrical properties of the compound have been studied. Anomalies in the temperature dependences of the electrical resistance and magnetic propoties have been found. These features are explained as martensitic phase transitions.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanova N. B., Kazak N. V., Michel C. R., Balaev A. D., Ovchinnikov S. G., Vasil'ev A. D., Bulina N. V., Panchenko E. B.
Заглавие : Effect of strontium and barium doping on the magnetic state and electrical conductivity of GdCoO3
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 49, Is. 8. - P1498-1506. - ISSN 1063-7834, DOI 10.1134/S1063783407080161
Примечания : Cited References: 36
Предметные рубрики: PEROVSKITE
ORDER
OXIDE
BEHAVIOR
GLASSES
LACOO3
PR
GD
SM
ND
Аннотация: A coordinated investigation of the magnetic and electrical properties of polycrystalline cobalt oxide compounds CdCoO3, Gd0.9Ba0.1CoO3, and Gd0.9Sr0.1CoO3 is carried out. Undoped GdCoO3 reveals a low conductivity; a magnetic moment of 7.4 mu(B) per molecule, which is less than the theoretical value for the Gd3+ ion; and an asymptotic Curie temperature of -6 K. Doping GdCoO3 with barium and strontium to substitution of 10 at. % Gd brings about an increase in the conductivity and magnetic transitions at T = 300 K for Gd0.9Ba0.1CoO3 and T = 170 K for Gd0.9Sr0.1CoO3. The magnetization anomalies imply the formation of magnetic clusters. The behavior of the electrical conductivity at high temperatures suggests a variable activation energy. At low temperatures, Mott hopping conduction sets in.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Gavrichkov V. A., Ovchinnikov S. G., Manske D., Eremin I.
Заглавие : Effective parameters of the band dispersion in n-type high-T-c superconductors
Разночтения заглавия :авие SCOPUS: Effective parameters of the band dispersion in n-type high-Tc superconductors
Место публикации : Physica C: ELSEVIER SCIENCE BV, 2004. - Vol. 402, Is. 4. - P365-370. - ISSN 0921-4534, DOI 10.1016/j.physc.2003.10.017
Примечания : Cited References: 32
Предметные рубрики: DOPED CUPRATE SUPERCONDUCTORS
TIGHT-BINDING METHOD
QUASI-PARTICLES
COPPER OXIDES
LA2-XSRXCUO4
SYMMETRY
MODEL
EVOLUTION
ORDER
Ключевые слова (''Своб.индексиров.''): high-t-c superconductivity--electronic correlations--electron-doped cuprates--electron-doped cuprates--electronic correlations--high-tc superconductivity--approximation theory--atomic physics--band structure--binding energy--charge transfer--correlation methods--doping (additives)--electronic structure--hamiltonians--mathematical models--mathematical operators--oxide superconductors--perturbation techniques--photoelectron spectroscopy--atomic orbitals--conduction band--electron doped cuprates--electron spins--valence band--high temperature superconductors
Аннотация: The electronic structure of electron-doped cuprates is discussed in the regions of small and optimal doping. For optimal doping we obtain the parameters from a simple tight-binding analysis by fitting ARPES data, and for small doping we study the band structure by the generalized tight-binding method that takes strong electronic correlations into account explicitly. This method has also reproduced well the ARPES data for small doping. The effective low-energy Hamiltonian is the t-t'-J model with hopping parameters t and t'. We compare both methods and find very good agreement for the value of t while t' is different because it is caused by the different contribution of the short-range spin correlations. (C) 2003 Elsevier B.V. All rights reserved.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Donkov A., Eremin I., Knolle J., Korshunov M. M.
Заглавие : Electron-Phonon Interaction and Phonon Renormalization in the Lamellar Cobaltate NaxCoO2
Разночтения заглавия :авие SCOPUS: Electron-phonon interaction and phonon renormalization in the lamellar cobaltate Na x CoO 2
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2009. - Vol. 22: International Conference on Quantum Phenomena in Complex Matters (JUL 26-AUG 01, 2008, Erice, ITALY), Is. 1. - P37-40. - ISSN 1557-1939, DOI 10.1007/s10948-008-0372-6
Примечания : Cited References: 16
Предметные рубрики: SUPERCONDUCTIVITY
Ключевые слова (''Своб.индексиров.''): electron-phonon interaction--superconductivity--sodium cobaltate--electron-phonon interaction--sodium cobaltate--superconductivity--brillouin zones--cobaltate--conducting electrons--conduction electrons--doping dependences--feedback effects--matrix elements--phonon frequencies--phonon modes--raman experiments--renormalization--sodium cobaltate--sodium cobaltates--atoms--cobalt compounds--critical current density (superconductivity)--electric conductivity--electron-phonon interactions--electrons--flow interactions--penetration depth (superconductivity)--sodium--superconductivity--phonons
Аннотация: We study theoretically the electron-phonon interaction in NaxCoO2. For the A(1g) and E-1g phonon modes found in Raman experiments, we calculate the matrix elements of the electron-phonon interaction. Analyzing the feedback effect of the conduction electrons on the phonon frequency., we investigate the doping dependence of these two phonon modes. Due to the momentum dependence of the electron-phonon interaction, we find the strongest renormalization of the E-1g mode around the Brillouin zone boundary which should be observed in the neutron scattering. At the same time, the A(1g) mode shows the strongest coupling to the conducting electrons around the G point and reveals its doping dependence in the Raman experiments. Our results shed light on the possible importance of the electron-phonon interaction in the lamellar sodium cobaltates.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Qiao J., Amachraa M., Molokeev M. S., Chuang Y. -C., Ong S. P., Zhang Q., Xia Z.
Заглавие : Engineering of K3YSi2O7 to Tune Photoluminescence with Selected Activators and Site Occupancy
Место публикации : Chem. Mater. - 2019. - Vol. 31, Is. 18. - P.7770-7778. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.9b02990
Примечания : Cited References: 48. - This work was supported by the National Natural Science Foundation of China (Nos. 51722202, 51972118 and 51572023), Natural Science Foundations of Beijing (2172036), Fundamental Research Funds for the Central Universities (FRF-TP-18-002C1), and Guangdong Provincial Science & Technology Project (2018A050506004). This work was also supported by the National Science Foundation, Ceramics Program (No. 1911372), and the computational resources were provided by the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the National Science Foundation (No. ACI-1548562).
Аннотация: The luminescence of rare earth ions (Eu2+, Ce3+, and Eu3+)-doped inorganic solids is attractive for the screening of phosphors applied in solid-state lighting and displays and significant to probe the occupied crystallographic sites in the lattice also offering new routes to photoluminescence tuning. Here, we report on the discovery of the Eu- and Ce-activated K3YSi2O7 phosphors. K3YSi2O7:Eu is effectively excited by 450 nm InGaN blue light-emitting diodes (LEDs) and displays an orange-red emission originated from characteristic transitions of both Eu2+ and Eu3+, while K3YSi2O7:Ce3+ shows green emission upon 394 nm near-ultraviolet (NUV) light excitation. Rietveld refinement verifies the successful doping of the activators, and density functional theory (DFT) calculations further support that Eu2+ occupies both K1 and Y2 crystallographic sites, while Ce3+ and Eu3+ only occupy the Y2 site; hence, the broad-band red emission of Eu2+ are attributed to a small DFT band gap (3.69 eV) of K3YSi2O7 host and a selective occupancy of Eu2+ in a highly distorted K1 site and a high crystal field splitting around Y2 sites. The white LEDs device utilizing orange-red-emitting K3YSi2O7:Eu and green-emitting K3YSi2O7:Ce3+ exhibits an excellent CRI of 90.1 at a correlated color temperature of 4523 K. Our work aims at bridging multivalent Eu2+/Eu3+ and Ce3+ site occupancy in the same host to realize photoluminescence tuning and especially exposes new ways to explore new phosphors with multicolor emission pumped by blue and NUV light for white LEDs.
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