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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Klyuchantsev A. B., Dzebisashvili D. M.
Заглавие : Quantum transport via dot devices with arbitrarily strong interactions
Колич.характеристики :22 с
Место публикации : Phys. Scr. - 2023. - Vol. 98, Is. 3. - Ст.035811. - ISSN 00318949 (ISSN), DOI 10.1088/1402-4896/acb61e. - ISSN 14024896 (eISSN)
Примечания : Cited References: 49. - The authors would like to thank V V Val'kov and S.V. Aksenov for fruitful discussions
Аннотация: The paper develops a theory of tunneling electron transport through atomic-scale systems (or briefly quantum dots) with arbitrarily strong interaction. The theory is based on a diagram technique for nonequilibrium Green’s functions defined on Hubbard operators. The use of Hubbard operators, describing many-body states of an entire quantum dot, makes it possible to represent the Hamiltonian of the quantum dot in a universal diagonal form and consider its coupling with two leads within the perturbation theory. It is shown that in the case when all Hubbard operators are defined for the same site, some rules of the diagram technique for Hubbard operators, initially developed for lattice models, have to be modified. As an example of the application of the modified theory, the current-voltage characteristics of the single-impurity Anderson model with infinitely large Coulomb repulsion are calculated. It is shown that taking into account the multiple electron tunneling processes with spin flips results in the dip in the center of the Lorentz distribution peak, describing the density of states of the one level Anderson impurity coupled with two leads. The emergence of this dip in the density of states leads to a peculiar feature in the bias voltage dependence of the differential conductivity, which can be detected experimentally.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Tetelbaum D., Nikolskaya A., Dorokhin M., Vasiliev V., Smolyakov D. A., Lukyanenko A. V., Baron F. A., Tarasov A. S.
Заглавие : Implanted gallium impurity detection in silicon by impedance spectroscopy
Место публикации : Mater. Lett. - 2022. - Vol. 308, Part B. - Ст.131244. - ISSN 0167577X (ISSN), DOI 10.1016/j.matlet.2021.131244
Примечания : Cited References: 11. - This study was supported by the Russian Foundation for Basic Research (grant No. 20-42-243007), Ministry of Science and Higher Education of the Russian Federation (project No. 075-03-2020-191/5), as well as the Government of the Russian Federation within the framework of the Megagrant for the creation of world-class laboratories (No. 075-15-2019-1886)
Аннотация: The results of determining the energy levels of boron-doped silicon implanted with gallium ions by impedance spectroscopy are reported. In the as-implanted sample the boron level remains the same and a second level appears close to the Ga-level reported in literature. In the sample annealed at 1000 °C, two levels are observed neither of which corresponds to the literature values for boron and gallium. It is assumed that in the as-implanted sample this method detects levels of gallium atoms located at a depth where ions penetrate due to the channeling effect, since a large concentration of defects at shallower depths does not allow detection of energy levels due to the Fermi level pinning. Explaining the results for the sample annealed after implantation requires additional research. The main result of this work is to establish the possibility of detecting impurity levels in ion-implanted silicon by impedance spectroscopy even in the absence of subsequent annealing.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Smolyakov D. A., Rautskii M. V., Bondarev I. A., Yakovlev I. A., Ovchinnikov S. G., Volkov N. V., Tarasov A. S.
Заглавие : Influence of a strong magnetic field on the ac transport properties of Fe/SiO2/n-Si MIS structure
Место публикации : J. Exp. Theor. Phys. - 2022. - Vol. 135, Is. 3. - P.377-382. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776122090102
Примечания : Cited References: 38. - The authors thank the administration of the Collective Use Center at the Krasnoyarsk Scientific Center (Siberian Division, Russian Academy of Sciences) for assistance. The authors also thank D.A. Balaev for valuable discussion and M.N. Volochaev for submission of PEM images. This study was supported by the Russian Foundation for Basic Research, Krasnoyarsk Region government, and Krasnoyarsk Region Foundation for research-and-engineering activity (grant no. 20-42-243007)
Аннотация: The ac transport properties of a Fe/SiO2/n-Si MIS structure made in the form of a Schottky diode have been studied in magnetic fields up to 9 T. A shift in the maxima of the temperature dependences of the impedance real part observed in the magnetic field is accompanied by the magnetoimpedance effect and takes place only at a certain relative orientation between the magnetic field and the surface of the sample. It has been found that the magnetoimpedance effect is related to the recharge of impurity states. Impurity state energy Es in the presence and absence of the magnetic field has been calculated. The impurity state energy is a nonlinear function of magnetic field and can be qualitatively characterized in terms of the theory of the Zeeman giant effect in diluted magnetic semiconductors. Other mechanisms of magnetic field influence on ac transport in MIS structures, specifically, on the impurity state recharge, cannot be disregarded either. This points calls for further investigation. Obtained data may provide a deeper insight into the nature of magnetoresistive effects in semiconductors and be used to design new-generation microelectronic devices.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Masyugin A. N., Kretinin V. V., Konovalov S. O., Shestakov N. P.
Заглавие : Magnetoresistance and IR spectrum of impurity states in the Ce3Fe5O12 film
Место публикации : Phys. Solid State. - 2021. - Vol. 63, Is. 2. - P.242-247. - ISSN 10637834 (ISSN), DOI 10.1134/S1063783421020025
Примечания : Cited References: 28. - This study was supported by the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Krai, and the Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project no. 18-42-240001 “Inversion of the Sign of Magnetoelectric Tensor Components with Temperature in the Neodymium-Doped Bismuth Iron Garnet Films”
Аннотация: In polycrystalline cerium iron garnet films, the gap in the electron excitation spectrum and electronic transitions between di- and tetravalent iron and cerium impurity ions have been established from the IR absorption spectra. The temperatures of delocalization of the ferrous states of iron have been found from the impedance spectroscopy, electrical resistance, and IR spectroscopy data. The difference between the ac and dc magnetoresistances has been established and explained using a model of a dielectrically inhomogeneous medium.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shestakov V. A., Korshunov M. M., Togushova Yu. N., Dolgov, O., V
Заглавие : Decisive proofs of the s± → s++ transition in the temperature dependence of the magnetic penetration depth
Коллективы : Russian Foundation for Basic Research (RFBR)Russian Foundation for Basic Research (RFBR) [19-32-90109]; RFBRRussian Foundation for Basic Research (RFBR); 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' [19-42-240007]
Место публикации : Supercond. Sci. Technol. - 2021. - Vol. 34, Is. 7. - Ст.075008. - ISSN 0953-2048, DOI 10.1088/1361-6668/abff6f. - ISSN 1361-6668(eISSN)
Примечания : Cited References: 40. - We are grateful to D V Efremov, A S Fedorov, S G Ovchinnikov, E I Shneyder, D Torsello, and A N Yaresko for useful discussions. This work was supported in part by the Russian Foundation for Basic Research (RFBR) Grant No. 19-32-90109 and by RFBR and Government of Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science to the Research Projects 'Electronic correlation effects and multiorbital physics in iron-based materials and cuprates' Grant No. 19-42-240007.
Предметные рубрики: ORDER-PARAMETER
IMPURITIES
SUPERCONDUCTORS
STATES
MODEL
Аннотация: One of the features of the unconventional s± state in iron-based superconductors is possibility to transform to the s++ state with the increase of the nonmagnetic disorder. Detection of such a transition would prove the existence of the s± state. Here we study the temperature dependence of the London magnetic penetration depth within the two-band model for the s± and s++ superconductors. By solving Eliashberg equations accounting for the spin-fluctuation mediated pairing and nonmagnetic impurities in the T-matrix approximation, we have derived a set of specific signatures of the s± → s++ transition: (1) sharp change in the behavior of the penetration depth λL as a function of the impurity scattering rate at low temperatures; (2) before the transition, the slope of ΔλL(T) = λL(T) - λL(0) increases as a function of temperature, and after the transition this value decreases; (3) the sharp jump in the inverse square of the penetration depth as a function of the impurity scattering rate, λL-2(Γa), at the transition; (4) change from the single-gap behavior in the vicinity of the transition to the two-gap behavior upon increase of the impurity scattering rate in the superfluid density ρs(T).
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Smolyakov D. A., Tarasov A. S., Bondarev M. A., Nikolskaya A. A., Vasiliev V. K., Volochaev M. N., Volkov N. V.
Заглавие : Admittance spectroscopy of dopants implanted in silicon and impurity state-induced AC magnetoresistance effect
Место публикации : Mater. Sci. Semicond. Process. - 2021. - Vol. 126. - Ст.105663. - ISSN 13698001 (ISSN), DOI 10.1016/j.mssp.2021.105663
Примечания : Cited References: 21. - This study was supported by the Government of the Russian Federation , Mega Grant for the Creation of Competitive World-Class Laboratories (Agreement no. 075-15-2019-1886)
Аннотация: A silicon structure doped with Ga using ion implantation has been investigated by admittance spectroscopy. It has been established that the presence of the Ga impurity, along with the B one, in the silicon structure leads to the appearance of the second peak in the temperature dependence of the real part of the impedance (admittance). Moreover, switching-on a magnetic field parallel to the sample plane shifts the singularities in the temperature curve to the high-temperature region. This results in the manifestation of both the positive and negative magnetoresistance effect upon temperature and magnetic field variation. It has been found by the standard admittance spectroscopy analysis of the impedance data that the energy structure of the investigated sample includes two interfacial energy levels ES1(0) = 42 meV and ES2(0) = 69.4 meV. As expected, these energies are consistent with the energies of B and Ga dopants. In a magnetic field, these levels increase by 3 meV for B and 2 meV for Ga, which induces the magnetoresistance effect. It has been demonstrated that the interfacial state-induced magnetoresistance effect can be tuned by ion implantation and dopant selection.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Onufrienok V. V., Chzhan A. V., Bondarenko G. V., Yurkin G. Yu.
Заглавие : Transition of metastable pyrrhotites to a stable phase state
Место публикации : Inorg. Mater. - 2020. - Vol. 56, Is. 9. - P.898-902. - ISSN 0020-1685, DOI 10.1134/S0020168520090137. - ISSN 1608-3172(eISSN)
Примечания : Cited References: 23
Предметные рубрики: MAGNETIC-PROPERTIES
TEMPERATURE
CHEMISTRY
Аннотация: Equilibrium phase relations of synthetic minerals prepared by annealing metastable iron sulfides, followed by prolonged isothermal storage in the Earth atmosphere, have been studied by X-ray diffraction. The results demonstrate that prolonged storage of synthetic pyrrhotites annealed at different temperatures makes it possible to identify metastable and stable phases of Fe and S compounds.
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8.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Korshunov M. M., Shestakov V. A.
Заглавие : Influence of temperature on the impurity-induced s±→s++ transition in the multiband model of Fe-based superconductors
Коллективы : Российская академия наук, Уральское отделение РАН, Институт физики металлов им. М. Н. Михеева Уральского отделения РАН, Уральский федеральный университет им. первого Президента России Б.Н. Ельцина, Российский фонд фундаментальных исследований, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : Euro-asian symposium "Trends in magnetism" (EASTMAG-2019): Book of abstracts/ чл. конс. ком.: S. G. Ovchinnikov, N. V. Volkov [et al.]; чл. прогр. ком. D. M. Dzebisashvili [et al.]. - 2019. - Vol. 2. - Ст.I.O4. - P.120. - ISBN 978-5-9500855-7-4 (Шифр В33/E12-125657784)
Примечания : Cited References: 3. - This work was supported by the “BASIS” Foundation for Development of Theoretical Physics and Mathematics, and the Krasnoyarsk Regional Fund of Science and Technology Support according to the participation in the VII Euro-Asian Symposium “Trends in Magnetism”: EASTMAG-2019
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yurkin G. Yu., Patrin G. S., Yarikov, Stanislav A.
Заглавие : Magnetic Properties of Fe1-xCoxSi Single Crystals at Low Co Impurity Concentrations
Место публикации : J. Sib. Fed. Univ. Math. Phys. - 2019. - Vol. 12, Is. 1. - P.94-99. - ISSN 1997-1397, DOI 10.17516/1997-1397-2019-12-1-94-99; \b Журнал СФУ. Математика и физика. - ISSN 2313-6022(eISSN)
Примечания : Cited References: 17
Ключевые слова (''Своб.индексиров.''): co impurities--iron silicide--superparamagnetism--силицид железа--примесь co--суперпарамагнетизм
Аннотация: Magnetostatic properties of FeSi and Fe0,98Co0,02Si single crystals have been studied. It has been found that the temperature and field dependences of the magnetization of monocrystal FeSi are strongly affected by introduction of a small amount of Co (2 %). A description of the results were provided by a model accounting for the formation of superparamagnetic iron clusters, as well as Fe-Co complexes. It is assumed that Fe-Co complexes form a ferromagnetic phase, which is approximately 0.6% of the Fe0,98Co0,02Si sample weight.В работе представлено исследование магнитостатических характеристик образцов FeSi и Fe0,98Co0,02Si. Обнаружено, что внесение небольшого количества примести Co(2%) значительно влияет на температурные и полевые зависимости намагниченности монокристалла FeSi. Результаты обработаны в рамках модели, учитывающей образование суперпарамагнитных кластеров железа, а также комплексов Fe-Co. Предполагается, что комплексы Fe-Co образуют ферромагнитную фазу, которая составляет примерно 0,6 % от массы образца Fe0,98Co0,02Si.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shestakov V. A., Korshunov M. M.
Заглавие : Influence of temperature on the impurity-induced s ± → s ++ transition in the two-band model for Fe-based superconductors
Коллективы : Euro-Asian Symposium "Trends in MAGnetism"
Место публикации : J. Phys. Conf. Ser. - 2019. - Vol. 1389, Is. 1. - Ст.012065. - ISSN 1742-6588, DOI 10.1088/1742-6596/1389/1/012065. - ISSN 1742-6596 (eISSN)
Примечания : Cited References: 45. - The reported study was funded by RFBR, project number 19-32-90109, and by the “BASIS” Foundation for Development of Theoretical Physics and Mathematics.
Аннотация: In Fe-based superconducting materials, the s ± state with the sign-changing gap in the clean limit could be changed to the sign-conserving s ++ state by nonmagnetic impurities. Previous results are obtained for the fixed temperature well below the superconducting critical temperature Tc . We study how the increasing temperature affects the transition between s ± and s ++ states in the two-band model. The calculations show that the s ± → s ++ transition appears to be dependent on temperature T, i.e. there exists a narrow range of impurity scattering rates, where the s ++ state in dirty superconductor at low temperature is transformed back to the s ± state by increasing T. With the nonmagnetic impurity scattering rate increasing, the temperature of such a reverse transition is shifted to Tc , while the s ++ state remains solely one for higher degree of disorder.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yurkin G. Yu., Patrin G. S., Yarikov S. A.
Заглавие : Magnetic Properties of Fe1-xCoxSi Single Crystals at Low Co Impurity Concentrations
Место публикации : J. Sib. Fed. Univ. Math. Phys. - 2019. - Vol. 12, Is. 6. - P.756-771. - ISSN 1997-1397, DOI 10.17516/1997-1397-2019-12-1-1-6; Журн. СФУ. Матем. и физика. - ISSN 2313-6022 (eISSN)
Примечания : Cited References: 17
Аннотация: Velocity of bulk acoustic waves in base and rotated cuts have been measured by the ultrasonic pulse-echo method and values of CE ijkl and eijk in single crystals YAl3(BO3)4 have been calculated. The value of dijk piezoelectric modulus of these single crystals have been determined by quasistatic measurements, and εσ ij dielectric constants have been determined by the flat capacitor method. Experimental values of material constants have been applied for the study of Magnetostatic properties of FeSi and Fe0;98Co0;02Si single crystals have been studied. It has been found that the temperature and field dependences of the magnetization of monocrystal FeSi are strongly affected by introduction of a small amount of Co (2 %). A description of the results were provided by a model accounting for the formation of superparamagnetic iron clusters, as well as Fe-Co complexes. It is assumed that Fe-Co complexes form a ferromagnetic phase, which is approximately 0.6% of the Fe0;98Co0;02Si sample weightВ работе представлено исследование магнитостатических характеристик образцов FeSi и Fe0;98Co0;02Si. Обнаружено, что внесение небольшого количества примести Co (2 %) значительно влияет на температурные и полевые зависимости намагниченности монокристалла FeSi. Результаты обрабобтаны в рамках модели, учетывающей образование суперпарамагнитных кластеров железа, а также комплексов Fe-Co. Предполагается, что комплексы Fe-Co образуют ферромагнитную фазу, которая составляет примерно 0,6 % от массы образца Fe0;98Co0;02Si.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Togushova Yu.N.
Заглавие : Effect of the spin-orbit coupling and impurity scattering on the spin resonance peak in three-orbital model for Fe-based superconductors
Место публикации : J. Sib. Fed. Univ. Math. Phys. - 2018. - Vol. 11, Is. 1. - P.108-116. - ISSN 19971397 (ISSN), DOI 10.17516/1997-1397-2018-11-1-108-116; Журн. СФУ. Сер. "Математика и физика"
Примечания : Cited References: 27
Аннотация: Here we study a combined effect of the spin-orbit coupling and scattering on the nonmagnetic disorder on the formation of the spin resonance peak in iron-based superconductors. Spin susceptibility is calculated within the random phase approximation. The spin resonance peak becomes broader with the increase of disorder and its frequency also shifts. At the same time, the spin response in the s state is different from that of the s++ state.Исследуется совместное влияние спин-орбитального взаимодействия и рассеяния на немагнитном беспорядке на формирование спин-резонансного пика в сверхпроводниках на основе железа. Спиновая восприимчивость вычислена в приближении хаотических фаз. Спин-резонансный пик становится шире с увеличением беспорядка, и его частота также смещается. В то же время спиновый отклик в состоянии s± отличается от такового в состоянии s++.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shestakov V. A., Korshunov M. M., Togushova Yu.N., Efremov D. V., Dolgov O. V.
Заглавие : Details of the disorder-induced transition between s± and s++ states in the two-band model for Fe-based superconductors
Коллективы : Russian Foundation for Basic Research [16-02-00098]; Government Support of the Leading Scientific Schools of the Russian Federation [NSh-7559.2016.2]; 'BASIS' Foundation for Development of Theoretical Physics and Mathematics
Место публикации : Supercond. Sci. Technol. - 2018. - Vol. 31, Is. 3. - Ст.034001. - ISSN 0953-2048, DOI 10.1088/1361-6668/aaa501. - ISSN 1361-6668(eISSN)
Примечания : Cited References:62. - We are grateful to P D Grigor'ev and M V Sadovskii for useful discussions. This work was supported in part by the Russian Foundation for Basic Research (grant 16-02-00098) and Government Support of the Leading Scientific Schools of the Russian Federation (NSh-7559.2016.2). MMK and VAS acknowledge the support of the 'BASIS' Foundation for Development of Theoretical Physics and Mathematics.
Предметные рубрики: IRON-BASED SUPERCONDUCTORS
HIGH-TEMPERATURE SUPERCONDUCTIVITY
PAIRING
Ключевые слова (''Своб.индексиров.''): unconventional superconductors--iron pnictides--iron chalcogenides--impurity scattering
Аннотация: IIrradiation of superconductors with different particles is one of many ways to investigate the effects of disorder. Here we study the disorder-induced transition between s ± and s ++ states in the two-band model for Fe-based superconductors with nonmagnetic impurities. Specifically, we investigate the important question of whether the superconducting gaps during the transition change smoothly or abruptly. We show that the behavior can be of either type and is controlled by the ratio of intraband to interband impurity scattering potentials, and by a parameter σ, that represents scattering strength and ranges from zero (Born approximation) to one (unitary limit). For the pure interband scattering potential and the scattering strength σ ≲ 0.11, the s ± → s ++ transition is accompanied by steep changes in the gaps, while for larger values of σ, the gaps change smoothly. The behavior of the gaps is characterized by steep changes at low temperatures, T˂ 0.1Tc0 with Tc0 being the critical temperature in the clean limit, otherwise it changes gradually. The critical temperature Tc is always a smooth function of the scattering rate in spite of the steep changes in the behavior of the gaps.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Rudenko V. V., Vorotynov A. M.
Заглавие : Weak ferromagnetism along the third-order axis of the FeBO3 crystals caused by Fe2+ impurity ions
Место публикации : J. Magn. Magn. Mater. - 2018. - Vol. 454. - P.139-143. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2018.01.037
Примечания : Cited References: 22
Ключевые слова (''Своб.индексиров.''): week ferromagnetism--magnetic anisotropy--impurity
Аннотация: Using the single-ion approximation, the weak ferromagnetic moment σZ(Fe2+) along the third-order axis of FeBO3 crystals, which is caused by the contribution of Fe2+ ions, has been investigated in the framework of the model Fe2+ impurity ion – vacancy. The extreme low-temperature behavior of the total magnetic moment due to the strong dependence of the Fe2+ion contribution is predicted.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shestakov V. A., Korshunov M. M., Dolgov O. V.
Заглавие : Temperature-dependent s± ↔ s++ transitions in the multiband model for Fe-based superconductors with impurities
Коллективы : Russian Foundation for Basic Research [16-02-00098]; Presidium of RAS Program for the Fundamental Studies [12]; "BASIS" Foundation for Development of Theoretical Physics and Mathematics; Gosbudget program [0356-2017-0030]
Место публикации : Symmetry. - Basel, 2018. - Vol. 10, Is. 8. - Ст.323. - ISSN 2073-8994, DOI 10.3390/sym10080323
Примечания : Cited References: 50. - This work was supported in part by the Russian Foundation for Basic Research (grant 16-02-00098), Presidium of RAS Program for the Fundamental Studies #12, and "BASIS" Foundation for Development of Theoretical Physics and Mathematics. MMK acknowledges support by the Gosbudget program #0356-2017-0030.
Предметные рубрики: IRON-BASED MATERIALS
Ключевые слова (''Своб.индексиров.''): unconventional superconductors--iron pnictides--iron chalcogenides--impurity scattering
Аннотация: We study the dependence of the superconducting gaps on both the disorder and the temperature within the two-band model for iron-based materials. In the clean limit, the system is in the s± state with sign-changing gaps. Scattering by nonmagnetic impurities leads to the change of the sign of the smaller gap, resulting in a transition from the s± to the s++ state with the sign-preserving gaps. We show here that the transition is temperature-dependent. Thus, there is a line of s±→s++ transition in the temperature–disorder phase diagram. There is a narrow range of impurity scattering rates, where the disorder-induced s±→s++ transition occurs at low temperatures, but then the low-temperature s++ state transforms back to the s± state at higher temperatures. With increasing impurity scattering rate, the temperature of such s++→s± transition shifts to the critical temperature Tc, and only the s++ state is left for higher amounts of disorder.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vorotynov A. M., Ovchinnikov S. G., Rudenko V. V.
Заглавие : Uniaxial and basal plane anisotropy caused by Cr2+ impurity ions in CrBO3 crystals
Место публикации : J. Phys. Chem. Solids. - 2018. - Vol. 123. - P.389-392. - ISSN 00223697 (ISSN), DOI 10.1016/j.jpcs.2018.08.016
Примечания : Cited References: 14
Ключевые слова (''Своб.индексиров.''): anisotropy--chromium compounds--crystal impurities--ions--single crystals
Аннотация: IIn this study, the uniaxial and basal anisotropy governed by Cr2+ impurity ions was treated based on the Cr2+– BO3 3− ion vacancy model using single ion approximation. The anomalous behavior of the basal anisotropy at low temperatures was predicted.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yakubailik E. K., Ganzhenko I. M., Balaev A. D., Butov, P. Yu.
Заглавие : Magnetic parameters of separation products and impurity aggregates in concentrates
Место публикации : J. Min. Sci. - 2017. - Vol. 53, Is. 6. - P.1133-1140. - ISSN 1062-7391, DOI 10.1134/S1062739117063233. - ISSN 1573-8736(eISSN)
Примечания : Cited References: 14
Ключевые слова (''Своб.индексиров.''): processing circuit--wet laboratory separation--concentrate impurity--magnetic characteristics
Аннотация: The changes in separation performance and magnetic characteristics of separation products is traced along the processing circuit of Abagur concentrator at a laboratory scale in order to determine the limit content of magnetite iron in impurity aggregates in the concentrate. The wet magnetic analysis is carried out in the field of H = 175 kA/m, and the magnetic characteristics are determined in the vibration magnetic detector in the field up to 800 kA/m. The concentrate impurity content is governed by the relative content of barren rock and ore aggregates removable in concentration at the given level of the technology.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Togushova Yu.N., Dolgov O. V.
Заглавие : Impurities in multiband superconductors
Место публикации : Physics-Uspekhi: Turpion, 2016. - Vol. 59, Is. 12. - P.1211-1240. - ISSN 10637869 (ISSN), DOI 10.3367/UFNe.2016.07.037863
Примечания : Cited References: 200. - We acknowledge partial support by RFBR (grant 16-02-00098) and Government Support of the Leading Scientific Schools of the Russian Federation (NSh-7559.2016.2).
Ключевые слова (''Своб.индексиров.''): unconventional superconductors--iron pnictides--iron chalcogenides--impurity scattering
Аннотация: Disorder impurities and defects violating the ideal long-range order is always present in solids. It can result in interesting and sometimes unexpected effects in multiband superconductors, especially if the superconductivity is uncon-ventional, thus having symmetry other than the usual s-wave. This paper uses the examples of iron-based pnictides and chal-cogenides to examine how both nonmagnetic and magnetic impurities affect superconducting states with s± and s++ order parameters. We show that disorder causes the transition between s± and s++ states and examine what observable effects this transition can produce. © 2016 Uspekhi Fizicheskikh Nauk, Russian Academy of Sciences.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Togushova, Yu. N., Shestakov V. A., Korshunov M. M.
Заглавие : Impurity-induced smearing of the spin resonance peak in Fe-based superconductors
Коллективы : RFBR [13-02-01395]; President Grant for Government Support of the Leading Scientific Schools of the Russian Federation [NSh-2886.2014.2]; Ministry of education and science of Russia [GF-2, SFU]
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2016. - Vol. 185, Is. 5-6. - P.481-487. - ISSN 0022-2291, DOI 10.1007/s10909-016-1577-x. - ISSN 1573-7357(eISSN)
Примечания : Cited References:25. - We acknowledge partial support by the RFBR (Grant 13-02-01395), President Grant for Government Support of the Leading Scientific Schools of the Russian Federation (NSh-2886.2014.2), and The Ministry of education and science of Russia (GF-2, SFU).
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
ELECTRONIC-STRUCTURE
IRON
Ключевые слова (''Своб.индексиров.''): fe-based superconductors--spin resonance peak--spin-orbit coupling--impurity scattering
Аннотация: The spin resonance peak in the iron-based superconductors is observed in inelastic neutron scattering experiments and agrees well with predicted results for the extended s-wave (s±) gap symmetry. On the basis of four-band and three-orbital tight-binding models we study the effect of nonmagnetic disorder on the resonance peak. Spin susceptibility is calculated in the random-phase approximation with the renormalization of the quasiparticle self-energy due to the impurity scattering in the static Born approximation. We find that the spin resonance becomes broader with the increase of disorder and its energy shifts to higher frequencies. For the same amount of disorder the spin response in the s± state is still distinct from that of the s++ state.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Togushova Yu. N., Dolgov O. V.
Заглавие : Uniform impurity scattering in two-band s ± and s ++ superconductors
Коллективы : RFBR [16-02-00098]; Leading Scientific Schools of the Russian Federation [NSh-2886.2014.2]
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 4. - С. 1089-1095. - ISSN 1557-1939, DOI 10.1007/s10948-016-3385-6. - ISSN 1557-1947(eISSN)
Примечания : Cited References:28. - We are grateful to D.V. Efremov and A. A. Golubov for useful discussions. We acknowledge the partial support by RFBR (Grant 16-02-00098) and President Grant for Government Support of the Leading Scientific Schools of the Russian Federation (NSh-2886.2014.2).
Предметные рубрики: High-temperature superconductivity
Iron
Ключевые слова (''Своб.индексиров.''): multiband superconductivity--impurity scattering--fe-based--superconductors
Аннотация: The s ± and s ++ models for the superconducting state are subject of intense studies regarding Fe-based superconductors. Depending on the parameters, disorder may leave intact or suppress T c in these models. Here, we study the special case of disorder with equal values of intra- and interband impurity potentials in the two-band s ± and s ++ models. We show that this case can be considered as an isolated point and T c there has maximal damping for a wide range of parameters.
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