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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aksenov S. V., Zlotnikov A. O., Shustin M. S.
Заглавие : Strong Coulomb interactions in the problem of Majorana modes in a wire of the nontrivial topological class BDI
Коллективы : RAS Presidium programs for fundamental research [32, 12]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-32-00443, 19-02-00348]; Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science [19-42-240011]; Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific SchoolsLeading Scientific Schools Program [MK-1641.2020.2, MK-3594.2018.2]; Foundation for the Advancement of Theoretical Physics and Mathematics "BASIS" [18-46-007]
Место публикации : Phys. Rev. B. - 2020. - Vol. 101, Is. 12. - Ст.125431. - ISSN 2469-9950, DOI 10.1103/PhysRevB.101.125431. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 60. - We acknowledge fruitful discussions with V. V. Valkov and V. A. Mitskan. The reported study was funded by the RAS Presidium programs for fundamental research Nos. 12 and 32, Russian Foundation for Basic Research (Projects No. 18-32-00443 and No. 19-02-00348), Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project: "Coulomb interactions in the problem of Majorana modes in low-dimensional systems with nontrivial topology" (Grant No. 19-42-240011). S.V.A. and A.O.Z. are grateful to the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools, Projects No. MK-1641.2020.2 and No. MK-3594.2018.2. S.V.A. acknowledges the support from the Foundation for the Advancement of Theoretical Physics and Mathematics "BASIS" (Grant No. 18-46-007).
Предметные рубрики: QUANTUM
POLARIZATION
TRANSITION
FERMIONS
SPECTRUM
STATE
Аннотация: In this study, the problem of strong Coulomb interactions in topological superconducting wire is analyzed by means of the density-matrix-renormalization-group (DMRG) approach. To analyze properties of edge states in the BDI-class structure, a quantity called Majorana polarization is used. From its dependence on wire length and an entanglement-spectrum degeneracy, topological phase diagrams are obtained. The DMRG calculations for the Shubin-Vonsovsky-type model of the wire show the transformation of phases with Majorana single and double modes (MSMs and MDMs, respectively) under the increase of onsite and intersite correlations. In particular, we demonstrate different scenarios including the possibilities of both induction and suppression of the MSMs and MDMs. It is shown that in the strongly correlated regime, the contributions of single-particle excitations to the Majorana-type states significantly decrease at low magnetic fxields. Moreover, the t-J*-V model is derived allowing to study the effective interactions and improve the DMRG numerics. It is found out that in the limiting case of the effective Hamiltonian with infinitely strong onsite repulsion, t model, the topological phases are destroyed. Finally, the ways to probe the MSMs and MDMs via the features of caloric functions are discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Stolyar S. V., Chekanova L. A., Vazhenina I. G.
Заглавие : Spin-Wave Resonance in One-Dimensional Magnonic Crystals by an Example of Multilayer Co-P Films
Место публикации : Phys. Solid State. - 2020. - Vol. 62, Is. 10. - P.1861-1867. - ISSN 1063-7834, DOI 10.1134/S1063783420100121. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 47
Предметные рубрики: FERROMAGNETIC-RESONANCE
SPECTRUM
MODES
INHOMOGENEITIES
Аннотация: Layered magnetic films of Co–P alloy, which are sets of laminates with certain atomic and chemical structures, have been investigated by spin-wave resonance. Coatings of two types were synthesized: a magnonic crystal (amorphous Co(P)/fcc Co(P))N and gradient Co(P) films. They exhibit two different modifications of the spin-wave resonance (SWR) spectrum. In the first case, the SWR spectrum is described as Hn(n) ~ n2 with a modification caused by the formation of the first stop band of the magnonic crystal. In the second case, the dependence of resonance fields Hn of the spin-wave modes on mode number n has the form of Hn(n) ~ n2/3. Thermal annealing leads to crystallization (amorphous alloy → fcc) and causes transformation of the layered films to the films of single-phase Co–P alloys, which is accompanied by a change in the shapes of the SWR spectra and occurrence of a “exchange kink” spectral modification.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vazhenina I. G., Iskhakov R. S., Milyaev M. A., Naumova L. I., Rautskii M. V.
Заглавие : Spin Wave Resonance in the [(Co0.88Fe0.12)/Cu]N Synthetic Antiferromagnet
Коллективы : Ministry of Science and Higher Education of the Russian Federation [AAAA-A18-118020290104-2]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [20-42-660018]
Место публикации : Tech. Phys. Lett. - 2020. - Vol. 46, Is. 11. - P.1076-1079. - ISSN 1063-7850, DOI 10.1134/S1063785020110140. - ISSN 1090-6533(eISSN)
Примечания : Cited References: 19. - This study was carried out under a state order of the Ministry of Science and Higher Education of the Russian Federation (theme "Spin" no. AAAA-A18-118020290104-2) and supported in part by the Russian Foundation for Basic Research (project no. 20-42-660018)
Предметные рубрики: MAGNETIC-PROPERTIES
MAGNETORESISTANCE
SPECTRUM
FILMS
Аннотация: The [(Co0.88Fe0.12)/Cu]N synthetic antiferromagnet has been investigated by the spin wave resonance method over the entire range of angles of an external dc magnetic field to the film surface normal. The investigations have shown that the superlattice under study consists of two exchange-coupled magnetic subsystems, each manifested in the recorded spectra as a series of spin-wave modes. The dependence of the linear region of propagation of a standing spin-wave mode on the sample orientation in an external magnetic field has been established.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorelik V. S., Pyatyshev, A. Yu., Krylov A. S.
Заглавие : Raman light scattering in sodium nitrite crystals
Коллективы : Russian Foundation for Basic Research [12-02-00491, 13-02-00449, 13-02-90420, 14-02-00190]
Место публикации : Bull. Lebedev Phys. Inst.: Allerton Press, 2016. - Vol. 43, Is. 5. - P.167-173. - ISSN 1068-3356, DOI 10.3103/S1068335616050043. - ISSN 1934-838X(eISSN)
Примечания : Cited References:37. - This study was supported by the Russian Foundation for Basic Research, projects nos. 12-02-00491, 13-02-00449,13-02-90420, 14-02-00190.
Предметные рубрики: NANO2
PHASE
SPECTROSCOPY
PARAPHOTONS
DEPENDENCE
SPECTRUM
SEARCH
Ключевые слова (''Своб.индексиров.''): sodium nitrite--raman scattering--spectrum--polar mode--polariton--ferroelectric--dispersion curves
Аннотация: Raman light scattering spectra of a ferroelectric sodium nitrite crystal is studied in the lattice mode region as the temperature is lowered from room temperature to 123 K. The existence of a Raman satellite corresponding to the soft lattice mode, i.e., transverse polar vibration responsible for the ferroelectric phase transition, is established for the first time. It is found that the intensity of the Raman scattering by the pseudo-scalar low-frequency A (2) mode exceeds the intensity of other lattice variations by an order of magnitude.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Klimin S. A., Kashchenko M. A., Bezmaternykh L. N.
Заглавие : Spin-phonon and electron-phonon interactions in multiferroic GdFe3(BO3)4 and TbFe3(BO3)4 evidenced by IR reflection spectroscopy
Коллективы : Russian Science Foundation [14-12-01033]; Swiss National Science Foundation (SNSF); Science and Technology cooperation program "Switzerland-Russia" of the University of Geneva
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2016. - Vol. 185, Is. 5-6. - P.538-543. - ISSN 0022-2291, DOI 10.1007/s10909-016-1597-6. - ISSN 1573-7357(eISSN)
Примечания : Cited References:19. - The authors thank Alexey Kuzmenko and Marina Popova for fruitful discussions. This paper was supported by the Russian Science Foundation under Grant No. 14-12-01033, by the Swiss National Science Foundation (SNSF), and by the Science and Technology cooperation program "Switzerland-Russia" of the University of Geneva.
Предметные рубрики: PHASE-TRANSITIONS
GdFe3(BO3)4
CRYSTALS
SPECTRUM
Ключевые слова (''Своб.индексиров.''): multiferroics--ir-active phonons--spin-phonon interaction--coupled--electron-phonon mode
Аннотация: We study temperature-dependent polarized reflection spectra of multiferroic GdFe3(BO3)4 and TbFe3(BO3)4 single crystals. Signatures of spin–lattice interactions in both compounds and of a formation of the electron–phonon coupled mode in TbFe3(BO3)4 are discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorelik V. S., Pyatyshev A. Y., Krylov A. S.
Заглавие : Raman scattering in sodium nitrite crystals near the phase transition
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 58, Is. 1. - P.170-176. - ISSN 10637834 (ISSN), DOI 10.1134/S1063783416010133
Примечания : Cited References: 39. - This study was supported by the Russian Foundation for Basic Research (project nos. 12-02-00491, 13-02-00449, 13-02-90420, and 14-02-00190).
Предметные рубрики: NaNO2
SPECTROSCOPY
DEPENDENCE
SPECTRUM
SEARCH
MODES
Аннотация: Optical Raman spectra of a ferroelectric sodium nitrite crystal have been detected in a wide spectrum range at various temperatures, including the region of the ferroelectric phase transition. A manifestation of a transverse soft polar mode of the A1(z) type responsible for the ferroelectric phase transition has been discovered in the spectrum at room temperature. This mode has been found to become overdamped even far from the ferroelectric phase transition temperature. This mode also appears as a central peak under heating. It has been found that the pseudoscalar mode of the A2 type has the highest intensity in the Raman spectrum of sodium nitrite. The frequency corresponding to the maximum intensity of this mode in the Raman spectrum varies from 130 cm–1 at 123 K to 106 cm–1 at T = 513 K. A fair agreement of the experimental data for the A1(z) mode with the Lyddane–Sachs–Teller relation has been established. The polariton curves for the A1(z) polar mode and the dispersion curves for axinons has been plotted. © 2016, Pleiades Publishing, Ltd.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G.
Заглавие : Temperature dependence of the electronic structure of La2CuO4 in the multielectron LDA+GTB approach
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 121, Is. 3. - P.457-464. - ISSN 1063-7761, DOI 10.1134/S1063776115090174
Примечания : Cited References: 38. - The work was supported by the Russian Science Foundation (project no. 14-12-00061)
Предметные рубрики: Copper oxides
Model
Superconductivity
Excitations
Instability
Spectrum
States
Order
Аннотация: The band structure of La2CuO4 in antiferromagnetic and paramagnetic phases is calculated at finite temperatures by the multielectron LDA+GTB method. The temperature dependence of the band spectrum and the spectral weight of Hubbard fermions is caused by a change in the occupation numbers of local multielectron spin-split terms in the antiferromagnetic phase. A decrease in the magnetization of the sublattice with temperature gives rise to new bands near the bottom of the conduction band and the top of the valence band. It is shown that the band gap decreases with increasing temperature, but La2CuO4 remains an insulator in the paramagnetic phase as well. These results are consistent with measurements of the red shift of the absorption edge in La2CuO4 with increasing temperature. © 2015, Pleiades Publishing, Inc.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Mitskan V. A., Korovushkin M. M.
Заглавие : The Kohn-Luttinger effect and anomalous pairing in new superconducting systems and graphene
Коллективы : Physics Department of the Russian Academy of Sciences [P.3.1]; Russian Foundation for Basic Research [14-02-00058, 14-02-31237]; Russian Federation [MK-526.2013.2]; Dynasty Foundation
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2014. - Vol. 118, Is. 6. - P.995-1011. - ISSN 1063-7761, DOI 10.1134/S1063776114060132. - ISSN 1090-6509
Примечания : Cited References: 114. - This study was supported by the Program of the Physics Department of the Russian Academy of Sciences (project no. P.3.1) and the Russian Foundation for Basic Research (project nos. 14-02-00058 and 14-02-31237). The work of two coauthors (M. M. K. and V.A.M) was supported financially by grant no. MK-526.2013.2 of the President of the Russian Federation and the Dynasty Foundation.
Предметные рубрики: P-WAVE SUPERCONDUCTIVITY
EXTENDED HUBBARD-MODEL
NARROW ENERGY-BANDS
2D KONDO-LATTICE
FERMI GAS
REPULSIVE INTERACTIONS
ELECTRON CORRELATIONS
COOPER INSTABILITY
PHASE-DIAGRAM
SPECTRUM
Аннотация: We present a review of theoretical investigations into the Kohn-Luttinger nonphonon superconductivity mechanism in various 3D and 2D repulsive electron systems described by the Fermi-gas, Hubbard, and Shubin-Vonsovsky models. Phase diagrams of the superconducting state are considered, including regions of anomalous s-, p-, and d-wave pairing. The possibility of a strong increase in the superconducting transition temperature T c even for a low electron density is demonstrated by analyzing the spin-polarized case or the two-band situation. The Kohn-Luttinger theory explains or predicts superconductivity in various materials such as heterostructures and semimetals, superlattices and dichalcogenides, high-T c superconductors and heavy-fermion systems, layered organic superconductors, and ultracold Fermi gases in magnetic traps. This theory also describes the anomalous electron transport and peculiar polaron effects in the normal state of these systems. The theory can be useful for explaining the origin of superconductivity and orbital currents (chiral anomaly) in systems with the Dirac spectrum of electrons, including superfluid 3He-A, doped graphene, and topological superconductors.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Sidorov K. A., Shneyder E. I.
Заглавие : Anomalous thermodynamics of the doped Mott-Hubbard insulators
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 53, Is. 2. - P299-302. - ISSN 1063-7834, DOI 10.1134/S1063783411020247
Примечания : Cited References: 6. - This study was supported by the Russian Foundation for Basic Research (project no. 09-02-00127), the Branch of the Physical Sciences of the Russian Academy of Sciences (program nos. 2 and 3), grant no. MK-1683.2010.2, and by the Federal Target Program "Personnel" (project NK-589 P).
Предметные рубрики: T-J MODEL
SPECTRUM
Аннотация: The concentration dependence of the entropy of doped Mott-Hubbard insulators has been considered within the t-J model. It has been shown that a change in the type and statistics of charge carriers as compared to the Fermi gas leads to a radical change in the entropy s, in particular, to the giant growth of the entropy upon doping. The quantity a,s/a,x a parts per thousand k (B) is approximately consistent with the experimental data for HTSC cuprates in the pseudogap phase.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pisarev R. V., Kalashnikova A. M., Schops O., Bezmaternykh L. N.
Заглавие : Electronic transitions and genuine crystal-field parameters in copper metaborate CuB2O4
Разночтения заглавия :авие SCOPUS: Electronic transitions and genuine crystal-field parameters in copper metaborate CuB 2O 4
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2011. - Vol. 84, Is. 7. - Ст.75160. - ISSN 1098-0121, DOI 10.1103/PhysRevB.84.075160
Примечания : Cited References: 65. - Useful discussions with W. Weber on crystal-field splitting of 3d states in cuprates are appreciated. We thank H.-J. Weber for the help in using Cary 2300 spectrophotometer. This work is supported by the Russian Foundation for Basic Research (project No. 09-02-00070) and Federal Agency for Science and Innovations (Grant No. 02.740.11.0384). A. M. K. acknowledges the financial support from the Committee for Science and Higher Education of the Government of Saint Petersburg.
Предметные рубрики: OPTICAL-ABSORPTION
PHASE-DIAGRAM
CUGEO3
SPECTRUM
SUPERCONDUCTORS
EXCITATIONS
SR2CUO2CL2
SCATTERING
LA2CUO4
CUPRATE
Аннотация: We present and analyze high-resolution alpha-, sigma-, and pi-polarized absorption spectra related to d-d electronic transitions in tetragonal metaborate CuB2O4 where copper Cu2+ ions occupy two crystallographically distinct 4b and 8d positions. The spectra are characterized by exceptionally rich fine structure in the spectral range of 1.4-2.4 eV. Six zero-phonon (ZP) lines originating from the electronic transitions within the Cu2+ ions in both positions are distinguished and identified. Symmetry analysis explains polarization properties of the ZP lines in the 8d positions but only partially explains them in the 4b positions. Reliable assignment of all six ZP lines to specific transitions allowed us to calculate genuine cubic Dq and tetragonal Ds and Dt crystal-field parameters for both positions. We show that the (3r(2) - z(2)) state, the energy of which is the measure of the Jahn-Teller splitting, is the highest 3d state for both types of Cu2+ ion positions. Using the obtained crystal-field parameters as the reference values, we estimated Dq, Ds, and Dt for several other cuprates with different Cu-O bond lengths. In particular, the 3d level splitting in La2CuO4, Nd2CuO4, CuGeO3, Sr2CuO2Cl2, and Cu3B7O13Cl was analyzed. Our estimates suggest that the Jahn-Teller splitting in some of these cuprates is larger than it was assumed previously.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Stolyar S. V., Chizhik M. V., Chekanova L. A.
Заглавие : Spin-Wave Resonance in Multilayer Films (One-Dimensional Magnon Crystals). Identification Rules
Место публикации : JETP Letters. - 2011. - Vol. 94, Is. 4. - P.301-305. - ISSN 0021-3640, DOI 10.1134/S0021364011160077
Примечания : Cited References: 17. - This work was supported by the Ministry of Education and Science of the Russian Federation, project no. RNP 2.1.1/3498, program "Development of Scientific Potential of Higher Schools" for 2009 and 2010 and the program "Scientific and Pedagogical Personnel of Innovative Russia" for 2009-2013. We are grateful to Prof. V. A. Ignatchenko for stimulating discussions.
Предметные рубрики: SPECTRUM
ALLOYS
Аннотация: The characteristic modification of the spectrum of the exchange spin waves has been revealed in ferromagnet/ferromagnet multilayer films with a thickness of N(d(1) + d(2)) by the spin-wave resonance method. This modification is due to the first bandgap at the wavenumber k(b) = pi/(d(1) + d(2)) of a magnon crystal, which is formed by one-dimensional modulation of the magnetization. It has been shown that the transformation of the multilayer film with thermal annealing to the film of a single-phase alloy is accompanied by the disappearance of this modification of the spectrum. DOI: 10.1134/S0021364011160077
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G.
Заглавие : Effect of Interlayer Single-Particle Hoppings on the Superconducting Transition Temperature
Разночтения заглавия :авие SCOPUS: Effect of interlayer single-particle hoppings on the superconducting transition temperature
Место публикации : JETP Letters. - 2011. - Vol. 93, Is. 6. - P.339-343. - ISSN 0021-3640, DOI 10.1134/S0021364011060063
Примечания : Cited References: 27. - This work was supported by the Presidium of the Russian Academy of Sciences (program no. 18.7 "Quantum Physics of Condensed Matter"), by the Siberian and Ural Branches of the Russian Academy of Sciences (joint project no. 40), by the Russian Foundation for Basic Research (project no. 09-02-00127), by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (project no. MK-1683.2010.2), and by the Ministry of Education and Science of the Russian Federation (project no. GK P891, federal program "Scientific and Pedagogical Personnel of Innovative Russia").
Предметные рубрики: T-J MODEL
DEPENDENCE
YBA2CU3O7-DELTA
ELECTRON
SPECTRUM
STRESS
Аннотация: It is well known that the superconducting transition temperature of high-T-c cuprates depends on the number of CuO2 planes in the unit cell. The multilayer structure implies the possibility of interlayer hopping. Under the assumption that the interlayer hopping can be specified by the parameter t(perpendicular to)(k) = t(perpendicular to)(cos(k(x)) - cos(k(y)))(2), the quasiparticle excitation spectrum for the bilayer cuprate in the superconducting state has been determined in the framework of the t - t' - t '' - t(perpendicular to) - J* model using the generalized mean-field approximation. It turns out that the interlayer hoppings does not create any additional mechanism of the Cooper paring and does not lead to an increase in T-c. The splitting of the upper Hubbard quasiparticle band attributed to the interlayer hoppings is manifested as two peaks in the doping dependence of the superconducting transition temperature at temperatures below the maximum T-c value for a single-layer cuprate. It has been found that antiferromagnetic interlayer correlations suppress the interlayer splitting. This probably leads to the common doping dependence of T-c for both single-layer and bilayer cuprates.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Makarov I. A., Shneyder E. I.
Заглавие : Effect of interlayer tunneling on the electronic structure of bilayer cuprates and quantum phase transitions in carrier concentration and high magnetic field
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 2. - P288-302. - ISSN 1063-7761, DOI 10.1134/S106377611005119X
Примечания : Cited References: 64. - This study was supported financially by the program "Quantum Physics of Condensed Media" of the Presidium of the Russian Academy of Sciences (project no. 5.7), the integration projects of the Siberian Branch and the Ural Division of the Russian Academy of Sciences (project no. 40), the Russian Foundation for Basic Research (project no. 09-02-00127), the President of the Russian Federation (grant no. MK-1683.2010.2), and the Federal Target Program P891.
Предметные рубрики: T-J MODEL
HIGH-TEMPERATURE SUPERCONDUCTORS
DIMENSIONAL HUBBARD-MODEL
FERMI-SURFACE
COPPER OXIDES
GROUND-STATE
CUO2 PLANES
SPECTRUM
BAND
NMR
Ключевые слова (''Своб.индексиров.''): antibonding--bi-layer--bilayer cuprates--complex sequences--cuprates--doping levels--external magnetic field--field magnitude--hartree-fock approximations--high magnetic fields--lifshitz transition--main effect--orbitals--perturbation theory--quantum phase transitions--quantum transitions--single-layer structure--theoretical study--unit cells--carrier concentration--copper compounds--density functional theory--electronic properties--electronic structure--hartree approximation--magnetic fields--perturbation techniques--phase transitions--surface structure--quantum theory
Аннотация: We present a theoretical study of the electronic structure of bilayer HTSC cuprates and its evolution under doping and in a high magnetic field. Analysis is based on the t-t'-taEuro(3)-J* model in the generalized Hartree-Fock approximation. Possibility of tunneling between CuO2 layers is taken into account in the form of a nonzero integral of hopping between the orbitals of adjacent planes and is included in the scheme of the cluster form of perturbation theory. The main effect of the coupling between two CuO2 layers in a unit cell is the bilayer splitting manifested in the presence of antibonding and bonding bands formed by a combination of identical bands of the layers themselves. A change in the doping level induces reconstruction of the band structure and the Fermi surface, which gives rise to a number of quantum phase transitions. A high external magnetic field leads to a fundamentally different form of electronic structure. Quantum phase transitions in the field are observed not only under doping, but also upon a variation of the field magnitude. Because of tunneling between the layers, quantum transitions are also split; as a result, a more complex sequence of the Lifshitz transitions than in single-layer structures is observed.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zyryanov V. Ya., Myslivets S. A., Gunyakov V. A., Parshin A. M., Arkhipkin V. G., Shabanov V. F., Lee, Wei
Заглавие : Magnetic-field tunable defect modes in a photonic-crystal/liquid-crystal cell
Место публикации : Opt. Express. - 2010. - Vol. 18, Is. 2. - P.1283-1288. - JAN 18. - ISSN 1094-4087, DOI 10.1364/OE.18.001283
Примечания : Cited Reference Count: 15. - Гранты: This work was partially supported by the Russian Federal Grant No. 02.740.11.0220 and SB RAS Grant Nos. 5, 27.1 and 144. W. Lee gratefully acknowledges financial support from the National Science Council of the Republic of China (Taiwan) under Grant No. NSC 98-2923-M-033-001-MY3 dedicated to an internationally joint effort between Russia and Taiwan.Финансирующая организация: Russian Federal [02.740.11.0220]; SB RAS [5, 27.1, 144]; National Science Council of the Republic of China (Taiwan) [NSC 98-2923-M-033-001-MY3]
Предметные рубрики: NEMATIC LIQUID-CRYSTAL
BAND-GAP MATERIALS
SPONTANEOUS EMISSION
SPECTRUM
Ключевые слова (''Своб.индексиров.''): crystal defects--magnetic fields--photonic crystals--applied magnetic fields--crossed polarizers--crystal cells--defect mode--homeotropic--light transmission spectra--light wave--nematic director--optical cells--planar alignment--spectral shift--tunable defect--light transmission--article--artifact--chemistry--electromagnetic field--liquid crystal--materials--materials testing--radiation exposure--refractometry--artifacts--electromagnetic fields--liquid crystals--manufactured materials--materials testing--refractometry
Аннотация: Light transmission spectrum of a multilayer photonic crystal with a central liquid-crystal defect layer placed between crossed polarizers has been studied. Transmittance was varied due to the magnetically induced reorientation of the nematic director from homeotropic to planar alignment. Two notable effects were observed for this scheme: the spectral shift of defect modes corresponding to the extraordinary light wave and its superposition with the ordinary one. As a result, the optical cell allows controlling the intensity of interfering defect modes by applied magnetic field. (C) 2010 Optical Society of America
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mankov Y. I., Tsikalov D. S.
Заглавие : High-frequency susceptibility of a multilayered ferromagnetic system with two-dimensional inhomogeneities
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 3. - P544-553. - ISSN 1063-7834, DOI 10.1134/S1063783410030157
Примечания : Cited References: 24. - This study was supported in part by the Council on Grants from the President of the Russian Federation for the State Support of Scientific Investigations performed by the Leading Scientific Schools (grant no. 3818.2008.3), the Presidium of the Russian Academy of Sciences (Program no. 27.1), and the Ministry of Education and Science within the framework of the Federal Program (State Contract no. 2.740.11.0220).
Предметные рубрики: SPIN-WAVE SUSCEPTIBILITY
SPECTRUM
SUPERLATTICES
INTERFACES
Аннотация: This paper reports on the results of the investigation of the high-frequency susceptibility of a layered ferromagnetic structure in which, apart from a periodic change in the magnetic anisotropy parameter from layer to layer, this parameter varies along layers according to a random law (the superlattice with two-dimensional phase inhomogeneities). The evolution of the frequency dependence of the imaginary part of the averaged Green's function in the range of the energy gap (band gap) in the spectrum of waves propagating along the superlattice axis due to the change in the relative root-mean-square fluctuations of the phase gamma 2 has been studied at the boundaries of the odd Brillouin zones. It has been found that, for all odd Brillouin zones, the imaginary part of the Green's function exhibits a universal behavior: the peak corresponding to the edge of the band gap with a lower frequency remains unchanged, and the peak corresponding to the edge of the band gap with a higher frequency is smoothed with an increase in the quantity gamma(2). These effects, which were initially revealed at the boundary of the first Brillouin zone of the sinusoidal superlattice, have been explained, as before, by the specific features of the energy conservation laws for the incident and scattered waves in the lattice with two-dimensional inhomogeneities. It has been demonstrated that an increase in the Brillouin zone number leads to a decrease in the value of gamma(2) at which the peak at the edge of the band gap with a higher frequency disappears.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Man'kov Yu. I., Tsikalov D. S.
Заглавие : High-frequency susceptibility of a multilayered ferromagnetic system with two-dimensional inhomogeneities
Место публикации : Phys. Solid State. - NEW YORK: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 3. - С. 544-553. - MAR. - ISSN 1063-7834, DOI 10.1134/S1063783410030157
Примечания : Cited Reference Count: 24. - Гранты: This study was supported in part by the Council on Grants from the President of the Russian Federation for the State Support of Scientific Investigations performed by the Leading Scientific Schools (grant no. 3818.2008.3), the Presidium of the Russian Academy of Sciences (Program no. 27.1), and the Ministry of Education and Science within the framework of the Federal Program (State Contract no. 2.740.11.0220).Финансирующая организация: Russian Federation [3818.2008.3]; Presidium of the Russian Academy of Sciences [27.1]; Ministry of Education and Science [2.740.11.0220]
Предметные рубрики: SPIN-WAVE SUSCEPTIBILITY
SPECTRUM
SUPERLATTICES
INTERFACES
Аннотация: This paper reports on the results of the investigation of the high-frequency susceptibility of a layered ferromagnetic structure in which, apart from a periodic change in the magnetic anisotropy parameter from layer to layer, this parameter varies along layers according to a random law (the superlattice with two-dimensional phase inhomogeneities). The evolution of the frequency dependence of the imaginary part of the averaged Green's function in the range of the energy gap (band gap) in the spectrum of waves propagating along the superlattice axis due to the change in the relative root-mean-square fluctuations of the phase gamma 2 has been studied at the boundaries of the odd Brillouin zones. It has been found that, for all odd Brillouin zones, the imaginary part of the Green's function exhibits a universal behavior: the peak corresponding to the edge of the band gap with a lower frequency remains unchanged, and the peak corresponding to the edge of the band gap with a higher frequency is smoothed with an increase in the quantity gamma(2). These effects, which were initially revealed at the boundary of the first Brillouin zone of the sinusoidal superlattice, have been explained, as before, by the specific features of the energy conservation laws for the incident and scattered waves in the lattice with two-dimensional inhomogeneities. It has been demonstrated that an increase in the Brillouin zone number leads to a decrease in the value of gamma(2) at which the peak at the edge of the band gap with a higher frequency disappears.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popova M. N., Stanislavchuk T. N., Malkin B. Z., Bezmaternykh L. N.
Заглавие : Breaking of the Selection Rules for Optical Transitions in the Dielectric PrFe3(BO3)(4) Crystal by a Praseodymium-Iron Exchange Interaction
Коллективы : RFBR [07-02-01185, 07-02-00704]; Russian Academy of Sciences
Разночтения заглавия :авие SCOPUS: Breaking of the selection rules for optical transitions in the dielectric PrFe3(BO3)4 crystal by a praseodymium-iron exchange interaction
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2009. - Vol. 102, Is. 18. - Ст.187403. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.102.187403
Примечания : Cited References: 26. - This work was supported in part by the RFBR under Grants No. 07-02-01185 and No. 07-02-00704 and by the Russian Academy of Sciences under the Programs for Basic Research.
Предметные рубрики: SINGLE-CRYSTAL
GDFE3(BO3)(4)
PHASE
DYFE3(BO3)(4)
SPECTRUM
LINES
Ключевые слова (''Своб.индексиров.''): magnetic ordering temperatures--optical spectrum--order parameters--point symmetries--selection rules--exchange interactions--neon--praseodymium--single crystals--crystal symmetry
Аннотация: We report on the emergence of new lines in the optical spectrum of the PrFe3(BO3)(4) single crystal at the magnetic ordering temperature. The transitions between singlet crystal-field sublevels of Pr3+ ion with the same transformational properties, strictly forbidden for the trigonal D-3 point symmetry of this ion in PrFe3(BO3)(4), appear below the Neel temperature and grow in intensity as a square of the order parameter. We show that the phenomenon originates from the mixing of wave functions of different Pr3+ sublevels by the Pr-Fe exchange interaction.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G., Shneider E. I.
Заглавие : Reconstruction of the Fermi surface of HTSC cuprates in a high magnetic field
Коллективы : Russian Foundation for Basic Research [09-02-00127]; Siberian Branch and the Ural Division, Russian Academy of Sciences [40]; Presidium of the Russian Academy of Sciences [5.7]
Место публикации : JETP Letters. - 2009. - Vol. 89, Is. 12. - P.632-637. - ISSN 0021-3640, DOI 10.1134/S002136400912008X
Примечания : Cited References: 19. - This work was supported by the Russian Foundation for Basic Research (project no. 09-02-00127), the Siberian Branch and the Ural Division, Russian Academy of Sciences (integration project no. 40), and the Presidium of the Russian Academy of Sciences (program no. 5.7).
Предметные рубрики: T-J MODEL
COPPER OXIDES
ELECTRON
SPECTRUM
BAND
Аннотация: The effect of a high magnetic field on the electronic structure of HTSC cuprates is considered. The study is performed in the t-t'-taEuro(3)-J* model, and the high magnetic field effect is taken into account not only as the Zeeman splitting of the one-electron levels, but also in the occupation numbers of the states with different spin projections and in the formation of the spin correlation functions. The field is assumed to be high enough to align all of the spins along the field. As a result, the Fermi surface reconstruction is obtained from four hole pockets about the nodal point (pi/2, pi/2) in the paramagnetic phase to a large hole pocket about the point (pi, pi) in the ferromagnetic phase. As the magnetic field strength decreases, a number of quantum phase transitions are revealed; they are manifested in the changed Fermi surface topology. The Fermi surface reconstruction with a decreasing field is qualitatively the same as that with an increasing doping degree in the absence of a magnetic field.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Shneyder E. I.
Заглавие : Lifshits Quantum Phase Transitions and Rearrangement of the Fermi Surface upon a Change in the Hole Concentration in High-Temperature Superconductors
Коллективы : Presidium of the Russian Academy of Sciences [5.7]; Russian academy of Sciences; Russian Foundation for Basic Research [09-02-00127]
Разночтения заглавия :авие SCOPUS: Lifshits quantum phase transitions and rearrangement of the fermi surface upon a change in the hole concentration in high-temperature superconductors
Место публикации : J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 5. - Pю775-785. - ISSN 1063-7761, DOI 10.1134/S1063776109110077
Примечания : Cited References: 71. - The authors thank A. A. Kordyuk for discussion of the results and T. M. Ovchinnikova for technical assistance in data processing.This study was supported by the program "Quantum Physics of Condensed Media" of the Presidium of the Russian Academy of Sciences (project no. 5.7), integrated project no. 40 of the Siberian Branch-Ural Division of the Russian academy of Sciences, and the Russian Foundation for Basic Research (project no. 09-02-00127).
Предметные рубрики: T-J MODEL
CORRELATED ELECTRONS
COPPER OXIDES
SPECTRUM
PSEUDOGAP
METAL
FLUCTUATIONS
EXCITATIONS
INSULATOR
SYSTEMS
Ключевые слова (''Своб.индексиров.''): critical points--cuprates--electron heat--electron structures--experimental data--high-t--layered cuprates--low temperatures--normal phase--quantum oscillations--quantum phase transitions--sign reversal--strong correlation--copper compounds--electronic structure--equations of state--fermi surface--fermions--high temperature superconductors--hole concentration--superconductivity--surface structure--phase transitions
Аннотация: Changes in the electronic structure in the normal phase of high-T-c superconductors (HTSCs), viz., layered cuprates, are considered. The results of LDA + GTB calculations of the electron structure and the Fermi surface of La2-xSrxCuO4 one-layer cuprates with allowance for strong correlations are compared with ARPES and quantum oscillations data. Two critical points x(c1) and x(c2) are discovered at which the rearrangement of the Fermi surface takes place. In the vicinity of these points, changes in the thermodynamic properties at low temperatures are determined using the Lifshits ideology concerning 2.5-order quantum phase transitions. A singularity delta(C/T) proportional to (x-x(e))(1/2) in the electron heat capacity agrees well with the available experimental data in the vicinity of x(c1)approximate to 0.15. Sign reversal of the Hall constant upon doping is also considered qualitatively.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Golovnya A. A.
Заглавие : Effect of Spin Fluctuations on the Superconducting Phase of Hubbard Fermions in the t-t'-t"-J* Model
Коллективы :
Разночтения заглавия :авие SCOPUS: Effect of spin fluctuations on the superconducting phase of Hubbard fermions in the t-t′-t″-J*model
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 107, Is. 6. - P996-1008. - ISSN 1063-7761, DOI 10.1134/S1063776108120091
Примечания : Cited References: 33. - This work was supported by the Program "Quantum Macrophysics" of the Presidium of the Russian Academy of Sciences, Russian Foundation for Basic Research (project no. 06.02.16100), and Integration project no. 3.4 of the Siberian Branch of the Russian Academy of Sciences.
Предметные рубрики: SPECTRUM
Ключевые слова (''Своб.индексиров.''): electric conductivity--fermions--integral equations--spin dynamics--spin fluctuations--anomalous components--critical temperatures--electron concentrations--hubbard--hubbard operators--joint effects--large systems--nonhomogeneous equations--one-loop approximations--order parameters--renormalization--scattering process--self energies--spin-fluctuation--strongly correlated electrons--superconducting phase--system of integral equations--superconductivity
Аннотация: The effect of spin-fluctuation scattering processes on the region of the superconducting phase in strongly correlated electrons (Hubbard fermions) is investigated by the diagram technique for Hubbard operators. Modified Gor'kov equations in the form of an infinitely large system of integral equations are derived taking into account contributions of anomalous components P(0 sigma),((sigma) over bar0) of strength operator P. It is shown that spin-fluctuation scattering processes in the one-loop approximation for the t-t'-t"-J* model taking into account long-range hoppings and three-center interactions are reflected by normal (P(0 sigma), (0 sigma)) and anomalous (P(0 sigma), ((sigma) over bar0)) components of the strength operator. Three-center interactions result in different renormalizations of the kernels of the integral equations for the superconducting d phase in the expressions for the self-energy and strength operators. In this approximation for the d-type symmetry of the order parameter for the superconducting phase, the system of integral equations is reduced to a system of nonhomogeneous equations for amplitudes. The resultant dependences of critical temperature on the electron concentrations show that joint effect of long-range hoppings, three-center interactions, and spin-fluctuation processes leads to strong renormalization of the superconducting phase region.
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