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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Val'kov V. V., Zlotnikov A. O., Fedoseev A. D., Shustin M. S.
Заглавие : A set of Majorana zero modes on the triangular lattice in the coexistence phase of superconductivity and noncollinear magnetic order
Коллективы : Days of the Condensed Matter University of Bordeaux, Journées de la matiére condensée
Место публикации : The 15th Days of the Condensed Matter (JMC'15): abstracts. - 2016. - P.45
Примечания : References: 4. - This study was funded by RFBR in part according to the research project No. 16-02-00073-a. A.O.Z. is grateful for support of the Grant of the President of the Russian Federation SP-1370.2015.5
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Aksenov S. V., Val'kov V. V., Ulanov E. A.
Заглавие : A Fano resonance in transport characteristics of 1D atomic spin structures
Коллективы : Институт теоретической физики им. Л. Д. Ландау РАН, Институт физики твердого тела РАН, "Mesoscopic and Strongly Correlated Electron Systems", conference (6; 2012 ; июнь ; 17-23; Черноголовка, Моск. обл.)
Место публикации : Book of abstracts of Advances Research Workshop "Meso–2012". - 2012. - P.37
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M.Yu., Val'kov V. V.
Заглавие : Anomalous resistivity and the electron-polaron effect in the two- band Hubbard model with one narrow band
Место публикации : arXiv. - 2011. - Ст.1111.3135
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Yu., Val'kov V. V.
Заглавие : Anomalous Resistivity and the Origin of Heavy Mass in the Two-Band Hubbard Model with One Narrow Band
Место публикации : J. Exp. Theor. Phys. - NEW YORK: PLEIADES PUBLISHING INC, 2011. - Vol. 113, Is. 1. - С. 156-171. - JUL. - ISSN 1063-7761, DOI 10.1134/S1063776111060021. - ISSN 1090-6509
Примечания : Cited Reference Count: 87. - RFBRRussian Foundation for Basic Research (RFBR) [08-02-00224, 08-02-00212]; Leverhulme trustLeverhulme Trust; CNRSCentre National de la Recherche Scientifique (CNRS)European Commission [236694], We are grateful to A. S. Alexandrov, A. F. Andreev, A. F. Barabanov, M. A. Baranov, Yu. Bychkov, A. V. Chubukov, D. V. Efremov, P. Fulde, A. S. Hewson, Yu. Kagan, K. A. Kikoin, K. I. Kugel, F. V. Kusmartsev, M. Mezard, Yu. E. Lozovik, P. Nozieres, N. V. Prokof'ev, A. L. Rakhmanov, T. M. Rice, A. O. Sboychakov, G. V. Shlyapnikov, P. Thalmeyer, C. M. Varma, D. Vollhardt, P. Woelfle, and A. Yaresko for the numerous simulating discussions on this subject and acknowledge financial support of the RFBR grants nos. 08-02-00224, 08-02-00212. M. Yu. K. is also grateful to Loughborough University (UK) and LPTMS (Orsay, France) for the hospitality during the final stage of this work and acknowledges financial support from the Leverhulme trust and CNRS (contract no. 236694).
Предметные рубрики: Physics, Multidisciplinary
Аннотация: We search for marginal Fermi-liquid behavior [1] in the two-band Hubbard model with one narrow band. We consider the limit of low electron densities in the bands and strong intraband and interband Hubbard interactions. We analyze the influence of electron polaron effect [2] and other mechanisms of mass enhancement (related to momentum dependence of the self-energies) on the effective mass and scattering times of light and heavy components in the clean case (electron-electron scattering and no impurities). We find the tendency towards phase separation (towards negative partial compressibility of heavy particles) in the 3D case for a large mismatch between the densities of heavy and light bands in the strong-coupling limit. We also observe that for low temperatures and equal densities, the homogeneous state resistivity R(T) similar to T-2 behaves in a Fermi-liquid fashion in both 3D and 2D cases. For temperatures higher than the effective bandwidth for heavy electrons T W-h*, the coherent behavior of the heavy component is totally destroyed. The heavy particles move diffusively in the surrounding of light particles. At the same time, the light particles scatter on the heavy ones as if on immobile (static) impurities. In this regime, the heavy component is marginal, while the light one is not. The resistivity saturates for T W-h* in the 3D case. In 2D, the resistivity has a maximum and a localization tail due to weak-localization corrections of the Altshuler-Aronov type [3]. Such behavior of resistivity could be relevant for some uranium-based heavy-fermion compounds like UNi2Al3 in 3D and for some other mixed-valence compounds possibly including layered manganites in 2D. We also briefly consider the superconductive (SC) instability in the model. The leading instability is towards the p-wave pairing and is governed by the enhanced Kohn-Luttinger [4] mechanism of SC at low electron density. The critical temperature corresponds to the pairing of heavy electrons via polarization of the light ones in 2D.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Korovushkin M. M., Barabanov A. F.
Заглавие : Competition of d- and s- wave superconductivity induced by exchange interactions in the spin-polaron ensemble
Коллективы : Moscow International Symposium on Magnetism, Московский государственный университет им. М.В. Ломоносова, Российский фонд фундаментальных исследований
Место публикации : Moscow Int. Symp. on Magnet. (MISM-2017): 1-7 July 2017 : book of abstracts. - 2017. - Ст.3OR-D-14. - P.359
Примечания : Cited References: 3. - The work was supported by the Russian Foundation for Basic Research (№ 16-02-00304), Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research (№ 16-42-240435, and 16-42-243057) and the grant of the President of the Russian Federation (Project MK-1398.2017.2)
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Korovushkin M. M., Barabanov A. F.
Заглавие : Coulomb repulsion of holes and competition between dx2−y2 -wave and s-wave parings in cuprate superconductors
Место публикации : J. Exp. Theor. Phys. - 2017. - Vol. 125, Is. 5. - P.810-821. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776117110085
Примечания : Cited References: 51. - This work was supported by the Russian Foundation for Basic Research, the Government of Kras-noyarsk Region, the Krasnoyarsk Region Science and Technology Support Fund (project nos. 16-42-240435, 16-42-243056, and 16-42-243057), and the Program by the Siberian Branch, Russian Academy of Sciences (project no. 356-2015-0406). The work of A.F.B. was supported by the Russian Foundation for Basic Research (project no. 16-02-00304). The work of M.M.K. was supported by the Council for Grants of the President of the Russian Federation (MK-1398.2017.2).
Ключевые слова (''Своб.индексиров.''): cooper instability--coulomb repulsions--crystallographic structure--inter-site coulomb interactions--order parameter symmetry--quasiparticles--self-consistency equations--super conducting phasis
Аннотация: The effect of the Coulomb repulsion of holes on the Cooper instability in an ensemble of spin–polaron quasiparticles has been analyzed, taking into account the peculiarities of the crystallographic structure of the CuO2 plane, which are associated with the presence of two oxygen ions and one copper ion in the unit cell, as well as the strong spin–fermion coupling. The investigation of the possibility of implementation of superconducting phases with d-wave and s-wave of the order parameter symmetry has shown that in the entire doping region only the d-wave pairing satisfies the self-consistency equations, while there is no solution for the s-wave pairing. This result completely corresponds to the experimental data on cuprate HTSC. It has been demonstrated analytically that the intersite Coulomb interaction does not affect the superconducting d-wave pairing, because its Fourier transform Vq does not appear in the kernel of the corresponding integral equation.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev A. D., Berzhanskii V. N., Valkov V. V., Ovchinnikov S. G., Chernov V. K.
Заглавие : Deviation from the bloch law in ferromagnetic materials with an intermediate valence
Место публикации : JETP Letters. - 1981. - Vol. 34, Is. 5. - P.255-258. - ISSN 0021-3640
Примечания : Cited References: 6
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Mitskan V. A., Korovushkin M. M., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Diagram Approach to the Problem of the Normal Phase Properties of the Spin-Polaron Ensemble in Cuprate Superconductors
Место публикации : J. Low Temp. Phys. - 2019. - Vol. 197, Is. 1-2. - P.34-43. - ISSN 00222291 (ISSN), DOI 10.1007/s10909-019-02211-9
Примечания : Cited References: 29. - The work was supported by the program of the Presidium of the Russian Academy of Sciences No. 12 “Fundamental problems of high-temperature superconductivity,” the Russian Foundation for Basic Research (RFBR) (Projects Nos. 18-02-00837 and 19-02-00509) and partly by the Government of Krasnoyarsk Region and the Krasnoyarsk Region Science and Technology Support Fund (Projects Nos. 18-42-243002 “Manifestation of spin-nematic correlations in spectral characteristics of electronic structure and their influence on practical properties of cuprate superconductors,” 18-42-243018 “Contact phenomena and magnetic disorder in the problem of the formation and detection of topological edge states in semiconductor nanostructures,” and 18-42-240014 “Single-orbit effective model of an ensemble of spin-polaron quasiparticles in the problem of describing the intermediate state and pseudogap behavior of cuprate superconductors”).
Аннотация: Taking into account the real crystalline structure of the CuO 2 plane within the spin-fermion model and using the diagram technique, the spin-polaron concept of the fermionic excitations in cuprate superconductors is implemented. It is shown that an account of the on-site scattering processes leads to considerable binding energy of the spin-polaron quasiparticles. An account of the two-site spin-fermion scattering processes results in the energy spectrum and spectral properties of the spin-polaron quasiparticles which agree well with experimental data on cuprate superconductors.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dzebisashvili D. M., Val'kov V. V., Barabanov A. F.
Заглавие : Fermi surface evolution in the ensemble of spin-polarized quasiparticles in La2 - xSrxCuO4
Место публикации : JETP Letters. - 2014. - Vol. 98, Is. 9. - P.528-533. - ISSN 0021-3640, DOI 10.1134/S0021364013220049. - ISSN 1090-6487
Примечания : Cited References: 36. - This work was supported by the Presidium of the Russian Academy of Sciences (program "Quantum Mesoscopic and Disordered Structures"), by the Russian Foundation for Basic Research (project nos. 13-02-00909, 13-02-00523, and 11-02-98007-Siberia), and by the Dynasty Foundation.
Предметные рубрики: SADDLE-POINT SINGULARITY
ANTIFERROMAGNETIC CORRELATIONS
CUPRATE SUPERCONDUCTORS
NORMAL-STATE
MODEL
BI2SR2CACU2O8+DELTA
YBA2CU3O6.9
LA2CUO4
EXCITATIONS
YBA2CU4O8
Аннотация: For the spin-fermion model, it has been shown that the concept of spin polarons makes it possible to reproduce fine details of the Fermi surface evolution in the nodal direction of La2-xSrxCuO4 occurring with changes in the doping level x. The physics here is determined by the spin-correlated hopping of charge carriers and by the doping dependence of the inverse magnetic correlation length. © 2013 Pleiades Publishing, Inc.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Val'kov V. V., Aksenov S. V., Zlotnikov A. O., Fedoseev A. D., Shustin M. S.
Заглавие : Edge states and Majorana modes in condensed matter
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.I1.14. - P.31. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 3
Ключевые слова (''Своб.индексиров.''): majorana fermions--edge states--triangular lattice--honeycomb lattice--electronic transport
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M.Yu., Val'kov V. V., Mitskan V. A., Korovushkin M. M.
Заглавие : Effect of long-range interactions on the Kohn-Luttinger mechanism of the cooper instability in the Shubin-Vonsowsky model
Место публикации : JETP letters. - 2013. - Vol. 97, Is. 4. - P.226-232. - DOI 10.1134/S0021364013040085
Аннотация: The problem of Cooper instability is studied by implementing the Kohn–Luttinger mechanism in the frame-work of the Shubin–Vonsowsky model taking into account the intersite Coulomb interactions within the first and second coordination spheres. It is shown that the Kohn–Luttinger renormalization for the effective interaction in the second order terms of perturbation theory, as well as the inclusion of intersite hoppings in the second and third coordination spheres, significantly affects the interplay between the superconducting phases with dxy-, p-, s-, and dx2-y2 -wave symmetries of the order parameter.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Aksenov S.V.
Заглавие : Effects of inelastic spin-dependent electron transport through a spin nanostructure in a magnetic field
Место публикации : J. Exp. Theor. Phys. - NEW YORK: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 113, Is. 2. - С. 266-275. - AUG. - ISSN 1063-7761, DOI 10.1134/S1063776111060070
Примечания : Cited Reference Count: 30. - Гранты: This study was carried out under the program of the Physical Science Department of the Russian Academy of Sciences, Federal Target Program "Scientific and Scientific-Pedagogical Personnel of Innovative Russia in 2009-2013," Interdisciplinary Integration project no. 53 of the Siberian Branch of the Russian Academy of Sciences, and under partial support from the Russian Foundation for Basic Research (project no. 09-02-00127). The research work of one of the authors (S.V.A) was supported by grant no. MK-1300.2011.2 from the President of the Russian Federation.Финансирующая организация: Russian Foundation for Basic Research [09-02-00127]; Russian Federation [MK-1300.2011.2]
Предметные рубрики: CONDUCTION
ANISOTROPY
JUNCTIONS
Ключевые слова (''Своб.индексиров.''): antiferromagnetic coupling--colossal magnetoresistance effect--iv characteristics--metallic contacts--potential profiles--spectral characteristics--spin dependent transport--spin dimer--spin moments--spin-dependent electron transport--spin-flip process--tight-binding approximations--transmission coefficients--antiferromagnetism--colossal magnetoresistance--current voltage characteristics--electric resistance--nanostructures--transport properties--magnetic field effects
Аннотация: The transport properties and current-voltage (I-V) characteristics of a system of spin dimers with antiferromagnetic coupling arranged between metallic contacts are investigated in the tight binding approximation using the Landauer-Buttiker formalism. It is shown that the s-d(f) exchange interaction between the spin moments of the electrons being transported and the spins of the nanostructure leads to the formation of a potential profile as well as its variation due to spin-flip processes. As a result, the spin-dependent transport becomes inelastic, and the transmission coefficient and the I-V characteristic are strongly modified. It is found that the application of a magnetic field induces additional transparency peaks in the spectral characteristic of the system and causes the colossal magnetoresistance effect.
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13.

Вид документа : Однотомное издание
Шифр издания :
Заглавие : Euro-asian symposium "Trends in magnetism" (EASTMAG-2004) : Abstract book
Выходные данные : Krasnoyarsk, 2004
Колич.характеристики :418 с
Коллективы : Российская академия наук, Сибирское отделение РАН, Институт физики им. Л.В. Киренского Сибирского отделения РАН, Красноярский государственный университет, Красноярский государственный технический университет, Институт физики металлов Уральского отделения РАН, Научный совет по физике конденсированных сред РАН, Научный совет РАН по физике низких температур, Красноярский научный центр Сибирского отделения РАН, Euro-asian symposium "Trends in magnetism" (2; 2004 ; Aug. 24-27; Krasnoyarsk), "Trends in magnetism", Euro-Asian Symposium (2; 2004 ; Aug. 24-27; Krasnoyarsk)
Примечания : Bibliogr. at the end of the articles - Auth. ind. :
Содержание : Fundamental magnetic properties ; Transport phenomena and spin electronics ; Magnetism and strongly correleted electron systems ; Spin glasses, disordered magnetic systems ; Dynamics of spin systems and magnetic resonances ; Magnetooptics and X-ray magnetooptics ; Magnetic mechanism of the superconductivity ; Domain structure and magnetization processes ; Thin magnetic films and multilayers ; Magnetic particles and nanocrystalline materials ; Molecular magnetism ; Magnetic storage/memory and applications
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Popkov S. I., Lavrov A. N., Kozeeva L. P., Kameneva M. Y., Val'kov V. V., Dzebisashvili D. M., Fedoseev A. D.
Заглавие : Features of the low-temperature specific heat in underdoped YBa2Cu3O6+x single crystals
Коллективы :
Разночтения заглавия :авие SCOPUS: Features of the low-temperature specific heat in underdoped YBa2Cu3O6 + x single crystals
Место публикации : JETP Letters. - 2010. - Vol. 92, Is. 5. - P.332-337. - ISSN 0021-3640, DOI 10.1134/S0021364010170133
Примечания : Cited References: 8. - The work was supported by the Siberian Branch, Russian Academy of Sciences (project no. 53, the Interdisciplinary Integration Program), by the Russian Foundation for Basic Research (project no. 10-02-00251), and by the Ministry of Education and Science of the Russian Federation (program "Scientific and Pedagogical Personnel of Innovative Russia" for 2009-2013). A.D.F. acknowledges the support of the Siberian Branch, Russian Academy of Sciences, provided in the framework of the Lavrent'ev Competition of the projects submitted by young researchers.
Аннотация: The behavior of the low-temperature specific heat C(T) for YBa2Cu3O6 + x single crystals with the doping level corresponding to the normal phase has been studied by the relaxation technique at different values of the applied magnetic field. It has been found that the C(T)/T plot exhibits such an anomaly as a steep increase with decreasing temperature from T about 4 K down to T a parts per thousand currency sign 2 K (the minimum temperature value accessible in the experiment). The applied magnetic field as high as 9 T inverts this anomaly and leads to a sharp drop in C(T)/T during cooling within the same temperature range. A model involving the Schottky-type centers formulated in this work and the data on spin correlation functions has allowed us to calculate the temperature dependence of the specific heat, which fits the experimental curves quite well.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Mitskan V. A., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Hierarchy of low-energy models of the electronic structure of cuprate HTSCs: The role of long-range spin-correlated hops
Коллективы : Russian fund for fundamental science, Government of the Krasnoyarsk region, Krasnoyarsk regional fund for scientific and technical activity [16-42-240435]; complex program SO RAN [P.2.P, 0356-2015-0405]; RFFI [16-02-00304]
Место публикации : Low Temp. Phys. - 2018. - Vol. 44, Is. 2. - P.130-138. - ISSN 1063-777X, DOI 10.1063/1.5020908. - ISSN 1090-6517(eISSN)
Примечания : Cited References: 42. - This study was conducted with financial support from the Russian fund for fundamental science, Government of the Krasnoyarsk region, Krasnoyarsk regional fund for scientific and technical activity in the framework of Project No. 16-42-240435 as well as the complex program SO RAN No. P.2.P (Project No. 0356-2015-0405). The work of A. F. Barabanov is supported by RFFI (Grant No. 16-02-00304).
Предметные рубрики: HIGH-TC SUPERCONDUCTORS
SINGLE-BAND MODELS
OXIDE SUPERCONDUCTORS
Аннотация: It is shown that for the three-band Emery p–d-model that reflects the real structure of the CuO2-plane of high-temperature superconductors in the regime of strong electron correlations, it is possible to carry out a sequence of reductions to the effective models reproducing low-energy features of elementary excitation spectrum and revealing the spin-polaron nature of the Fermi quasiparticles. The first reduction leads to the spin-fermion model in which the subsystem of spin moments, coupled by the exchange interaction and localized on copper ions, strongly interacts with oxygen holes. The second reduction deals with the transformation from the spin-fermion model to the φ–d-exchange model. An important feature of this transformation is the large energy of the φ–d-exchange coupling, which leads to the formation of spin polarons. The use of this fact allows us to carry out the third reduction, resulting in the t̃ −J̃∗−I-model. Its distinctive feature is the importance of spin-correlated hops as compared to the role of such processes in the commonly used t–J*-model derived from the Hubbard model. Based on the comparative analysis of the spectrum of Fermi excitations calculated for the obtained effective models of the CuO2-plane of high-temperature superconductors, the important role of the usually ignored long-range spin-correlated hops is determined.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shklyaev A. A., Korovushkin M. M., Barabanov A. F.
Заглавие : Influence of triplet states on the spectrum of collective spin-polaron excitations in a 2D kondo lattice
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 53, Is. 10. - P1997-2000. - ISSN 1063-7834, DOI 10.1134/S1063783411100337
Примечания : Cited References: 10. - This study was supported by the Presidium of the Russian Academy of Sciences (Program "Quantum Physics of Condensed Matter"), the Siberian Branch of the Russian Academy of Sciences (Interdisciplinary Integration project no. 53), the Ministry of Education and Science of the Russian Federation (Russian Federal Targeted Program "Scientific and Scientific-Pedagogical Personnel of the Innovative Russia" in 2009-2013), and the Russian Foundation for Basic Research (projects nos. 09-02-00127, 10-02-00614).
Предметные рубрики: SUPERCONDUCTIVITY
ANTIFERROMAGNET
Аннотация: The normal and superconducting phases of the ensemble of spin polarons in a two-dimensional Kondo lattice have been considered under the conditions when the hopping integral is comparable to the s-d exchange interaction energy. The polaron excitation spectrum and the superconducting transition temperature have been found taking into account upper triplet states. The change in the concentration dependence of the critical temperature of the transition to the superconducting phase with the relation between the hopping integral and the integral of the s-d exchange coupling has been analyzed.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Furrer A., Fisher P., Roessli B., Petrakovskii G. A., Sablina K. A., Valkov V. V., Fedoseev B.
Заглавие : Investigation of spin-waves in single-crystal Bi2CuO4 by inelastic neutron-scattering
Место публикации : Solid State Commun. - 1992. - Vol. 82, Is. 6. - P.443-446. - ISSN 0038-1098, DOI 10.1016/0038-1098(92)90746-V
Примечания : Cited References: 9
Аннотация: Neutron scattering experiments have been employed to study the spin-wave excitations and the critical behaviour of sublattice magnetization of a single crystal Bi2CuO4. Dispersion law for spin waves along the tetragonal axis of crystal is determined. There were found two branches of spin waves which are characterized by the energy gaps DELTA-1 congruent-to 1.7 meV and DELTA-2 congruent-to 4.0 meV, respectively. The value of critical exponent beta = 0.36 + 0.08 reflects the 3D character of the magnetic ordering in Bi2CuO4. Observed two spin-wave branches are described on the basis of the anisotropic tetragonal spin-Hamiltonian with four-sites exchange interaction.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Valkov V. V.
Заглавие : Anomalous resistivity and superconductivity in the two-band Hubbard model with one narrow band (Review)
Место публикации : Low Temp. Phys. - 2011. - Vol. 37, Is. 1. - P.69-82. - ISSN 1063-777X, DOI 10.1063/1.3552118; \b Физика низких температур
Примечания : Cited References: 62. - We thank A.S. Alexandrov, A.F. Andreev, M.A. Baranov, Yu. Bichkov, A.V. Chubukov, D.V. Efremov, A.S. Hewson, K.A. Kikoin, F.V. Kusmartsev, P. Nozieres, T.M. Rice, A.O. Sboychakov, P. Thalmeer, C.M. Varma, D. Vollhardt, P. Woelfle, A. Yaresko and, especially, P. Fulde, Yu. Kagan, K.I. Kugel, and N.V. Prokof'ev for many simulating discussions on this subject and acknowledge the financial support of RFBR grants # 08-02-00224 and 08-02-00212. M.Yu.K. is also grateful to the Leverhulme trust for a grant to visit Loughborough University, where this work was completed.
Предметные рубрики: FERMI-LIQUID BEHAVIOR
MAGNETIC-ALLOYS
HEAVY
DENSITY
SYSTEMS
STATE
UPT3
MECHANISM
PARTICLE
VALENCE
Аннотация: We search for marginal Fermi-liquid behavior in the two-band Hubbard model with one narrow band. We consider the limit of low electron densities in the bands and strong intraband and interband Hubbard interactions. We analyze the influence of electron-polaron effects and other mechanisms for mass-enhancement (related to the momentum dependence of the self-energies) on the effective mass and scattering times of light and heavy components in the clean case (electron-electron scattering and no impurities). We find a tendency towards phase separation (towards negative partial compressibility of heavy particles) in the 3D case with a large mismatch between the densities of heavy and light bands in the strong coupling limit. We also find that for low temperatures and equal densities, the resistivity in a homogeneous state R(T) proportional to T-2 behaves as a Fermi-liquid in both 3D and 2D. For temperatures greater than the effective bandwidth for heavy electrons T W-h*, the coherence of the heavy component breaks down completely. The heavy particles move diffusively in the surrounding light particles. At the same time, light particles scatter on heavy particles as if on immobile (static) impurities. Under these conditions, the heavy component is marginal, while the light component is not. The resistivity approaches saturation for T W-h* in the 3D case. In 2D the resistivity has a maximum and a localization tail owing to weak-localization corrections of the Altshuler-Aronov type. This behavior of resistivity in 3D could be relevant for some uranium-based heavy-fermion compounds such as UNi2Al3 and in 2D, for some other mixed-valence compounds, possibly including layered manganites. We also consider briefly the superconductive (SC) instability in this model. The leading instability tends to p-wave pairing and is governed by an enhanced Kohn-Luttinger mechanism for SC at low electron densities. The critical temperature corresponds to the pairing of heavy electrons via polarization of the light electrons in 2D. (C) 2011 American Institute of Physics. [doi:10.1063/1.3552118]
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V.
Заглавие : Anomalous resistivity and the electron-polaron effect in the two-band hubbard model with one narrow band
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2012. - Vol. 25, Is. 5. - P.1379-1382. - ISSN 1557-1939, DOI 10.1007/s10948-012-1523-3
Примечания : Cited References: 28. - We are grateful to P. Fulde, Yu. Kagan, K. I. Kugel, N.V. Prokof'ev, P. Nozieres, and C. M. Varma for the numerous stimulating discussions. We acknowledge financial support of the RFBR Grant No. 11-02-00741.
Предметные рубрики: FERMI GAS
SUPERCONDUCTIVITY
SUPERFLUIDITY
TEMPERATURE
REPULSION
SYSTEMS
Ключевые слова (''Своб.индексиров.''): electron-polaron effect--two-band hubbard model--marginality--anomalous resistivity
Аннотация: We search for anomalous normal and superconductive behavior in the two-band Hubbard model with one narrow band. We analyze the influence of the electron–polaron effect and the Altshuler–Aronov effect on effective mass enhancement and scattering times of heavy and light components in the clean case. We find anomalous behavior of resistivity at high temperatures TW∗hT W_{h}. *} both in 3D and 2D situations. The SC instability in the model is governed by an enhanced Kohn–Luttinger effect for p-wave pairing of heavy electrons via polarization of light electrons.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Woelfle P.
Заглавие : Manifestation of the upper Hubbard band in the 2D Hubbard model at low electron density
Место публикации : Low Temp. Phys. - 2011. - Vol. 37, Is. 9-10. - P.834-839. - ISSN 1063-777X, DOI 10.1063/1.3670026; \b Физика низких температур
Примечания : Cited References: 31. - This work was supported by RFBR Grants No. 11-0200798 and 11-02-00741.
Предметные рубрики: 2-DIMENSIONAL FERMI GAS
LIQUID BEHAVIOR
SPECTRAL FUNCTIONS
TRANSITION METALS
SUPERCONDUCTIVITY
FERROMAGNETISM
DIMENSIONS
SCATTERING
STATE
Ключевые слова (''Своб.индексиров.''): electron density--electronic density of states--fermi liquid--green's function methods--hubbard model
Аннотация: We consider the 2D Hubbard model in the strong-coupling case (U W) and at low electron density (nd(2) ≪1). We find an antibound state as a pole in the two-particle T-matrix. The contribution of this pole in the self-energy reproduces a two-pole structure in the dressed one-particle Green-function similar to the Hubbard-I approximation. We also discuss briefly the Engelbrecht-Randeria mode which corresponds to the pairing of two holes below the bottom of the band for U W and low electron density. Both poles produce nontrivial corrections to Landau Fermi-liquid picture already at low electron density but do not destroy it in 2D.
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