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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Карпов, Сергей Васильевич, Рассказов, Илья Леонидович
Заглавие : Моделирование условий синтеза оптических нановолноводов из цепочек сферических металлических наночастиц методом электростатической функционализации технологической подложки
Место публикации : Коллоид. журн. - 2013. - Т. 75, № 3. - С. 308-318. - DOI 10.7868/S0023291213030099
Аннотация: Для получения упорядоченных структур из близкорасположенных плазмонно-резонансных наночастиц предложен электростатический метод функционализации подложек, обеспечивающий избирательное осаждение на них наночастиц из объема коллоидной системы. Метод основан на размещении с обратной стороны подложки металлического наношаблона требуемой конфигурации, на который подается электрический потенциал. Разработана математическая модель, позволяющая определить соответствие условиям реального эксперимента тех параметров системы, которые обеспечивают осаждение металлических наночастиц в одномерные упорядоченные структуры на подложку из объема золя в неоднородном электрическом поле, создаваемом наношаблоном. С помощью модели броуновской динамики исследована зависимость степени дефектности синтезируемых цепочек от физико-химических и электрических параметров системы, определяющая пригодность такого типа структур для передачи оптического возбуждения на частоте поверхностного плазмона частиц. Приведены примеры расчетов спектральных и трансмиссионных свойств нановолноводов данного типа.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Karpov S. V., Рассказов, Илья Леонидович
Заглавие : Simulation of conditions for fabrication of optical nanowaveguides in the form of chains of spherical metal nanoparticles by electrostatic functionalization of the process substrate
Место публикации : Colloid J. - 2013. - Vol. 75, Is. 3. - P.279-288. - ISSN 1061-933X, DOI 10.1134/S1061933X13030083
Ключевые слова (''Своб.индексиров.''): deposition of metals--electrical parameter--experimental conditions--nonuniform electric field--ordered structures--selective deposition--single-domain structure--transmission property--deposition--electric fields--mathematical models--metal nanoparticles--photoexcitation--plasmons--sols--substrates
Аннотация: A method is proposed for electrostatic functionalization of substrates used to prepare ordered structures composed of closely spaced plasmon-resonant nanoparticles. The method ensures selective deposition of nanoparticles from the bulk of a colloidal system onto the substrates. This method is based on placing a metal nanotemplate of a required configuration at the opposite side of a substrate, with an electric potential being applied to the template. A mathematical model is developed to ensure that the system parameters responsible for the deposition of metal nanoparticles into ordered single-domain structures on the substrate from a bulk sol in a nonuniform electric field generated by the nanotemplate correspond to the real experimental conditions. Since the degree of imperfection of the synthesized chains governs the applicability of these structures to transmission of the optical excitation at the frequency of the surface plasmon of the particles, the dependence of the degree of imperfection on the physicochemical and electrical parameters of the system is studied using the Brownian-dynamics model. The calculations of the spectral and transmission properties of nanowaveguides of this type are exemplified. В© 2013 Pleiades Publishing, Ltd.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maksimov D. N., Sadreev A. F.
Заглавие : Symmetry breaking in binary chains with nonlinear sites
Место публикации : Phys. Rev. E. - 2013. - Vol. 88, Is. 3. - Ст.032901. - P. - ISSN 1539-3755, DOI 10.1103/PhysRevE.88.032901
Аннотация: We consider a system of two or four nonlinear sites coupled with binary chain waveguides. When a monochromatic wave is injected into the first (symmetric) propagation channel, the presence of cubic nonlinearity can lead to symmetry breaking, giving rise to emission of antisymmetric wave into the second (antisymmetric) propagation channel of the waveguides. We found that in the case of nonlinear plaquette, there is a domain in the parameter space where neither symmetry-preserving nor symmetry-breaking stable stationary solutions exit. As a result, injection of a monochromatic symmetric wave gives rise to emission of nonsymmetric satellite waves with energies differing from the energy of the incident wave. Thus, the response exhibits nonmonochromatic behavior. В© 2013 American Physical Society.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Рассказов, Илья Леонидович, Karpov S. V., Markel V. A.
Заглавие : Nondecaying surface plasmon polaritons in linear chains of silver nanospheroids
Место публикации : Opt. Lett. - 2013. - Vol. 38, Is. 22. - P.4743-4746. - ISSN 0146-9592, DOI 10.1364/OL.38.004743
Аннотация: We consider propagation of surface plasmon polaritons in linear chains of equidistant metallic nanospheroids. We show that, for suitably chosen parameters, the propagation is free of spatial decay in spite of the full account of absorptive losses in the metal. В© 2013 Optical Society of America.
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5.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Рассказов, Илья Леонидович, Markel V. A., Karpov S. V.
Заглавие : Propagation of surface plasmon polaritons in curved 2D chains of nanospheroids
Коллективы : International Conference on Coherent and Nonlinear Optics, International Conference on Lasers, Applications, and Technologies , Российская академия наук, Московский государственный университет им. М.В. Ломоносова
Место публикации : ICONO/LAT 2013 : Advance conference program. - 2013. - P.
,
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gurevich Y. L., Mankov Yu.I., Khlebopros R. G.
Заглавие : Self-assembly of superparamagnetic ferrihydrite nanoparticles
Коллективы : Russian Foundation for Basic Research [08-08-00427_a, 10-08-00278_a]; Siberian Branch, Russian Academy of Sciences, Integration project [21]
Место публикации : Dokl. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2013. - Vol. 58, Is. 11. - P.478-481. - ISSN 1028-3358, DOI 10.1134/S1028335813110104
Примечания : Cited References: 15. - This work was supported by the Russian Foundation for Basic Research, project nos. 08-08-00427_a and 10-08-00278_a, and by the Siberian Branch, Russian Academy of Sciences, Integration project no. 21.
Предметные рубрики: CHAINS
CLUSTERS
Аннотация: A study was conducted to estimate the possibility of formation of chains of superparamagnetic nanoparticles of iron oxyhydroxides synthesized in a bacteria culture. The self-assembly of biogenic nanoparticles distinguished by low values of magnetization and small sizes is assumed to proceed due to the forces of magnetic dipole dipole interaction as an initial mechanism of aggregation and exchange-interaction forces, which provide the stability of chains. The microphotographs demonstrate the self-assembly of anisotropic cobalt-doped ferrihydrite nanoparticles in aggregates of ellipsoidal shape with sizes of about 550 × 300 nm and a platelike shape of 50-100 nm thick. The aggregates, in turn, are combined from blocks, which include a restricted number of nanoparticles of about 5 nm in diameter and have the shape of rods of 50-100 × 12 nm in size. The energy of degaussing fields of chains is reasonably high, which forces them to form two and three dimensional structures in which the compensation of such fields is provided.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rasskazov I. L., Karpov S. V., Markel V. A.
Заглавие : Surface plasmon polaritons in curved chains of metal nanoparticles
Коллективы : US National Science Foundation [DMS1216970]; Russian Academy of Sciences [24.29, 24.31, III. 9.5, 43, SFU (101)]; Russian Ministry of Education and Science [1792]
Место публикации : Phys. Rev. B: American Physical Society, 2014. - Vol. 90, Is. 7. - Ст.75405. - ISSN 1098-0121, DOI 10.1103/PhysRevB.90.075405. - ISSN 1550-235X
Примечания : Cited References: 34. - This research was supported in part by the US National Science Foundation under Grant DMS1216970, by the Russian Academy of Sciences under the Grants 24.29, 24.31, III. 9.5, 43, SFU (101), and also by the Russian Ministry of Education and Science under the Contract 1792.
Предметные рубрики: LINEAR-CHAINS
DISPERSION-RELATIONS
ARRAYS
RESONANCES
FIELD
Аннотация: We investigate numerically the propagation of steady-state monochromatic surface plasmon polaritons (SPPs) in curved chains of metal nanoparticles of various spheroidal shapes. We discuss the SPP propagation (decay of the amplitude), the polarization conversion due to coupling of orthogonally polarized SPPs, and the electromagnetic field localization in the near-field vicinity of a chain.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rasskazov I. L., Karpov S. V., Markel V. A.
Заглавие : Waveguiding properties of short linear chains of nonspherical metal nanoparticles
Коллективы : U.S. National Science Foundation [DMS1216970]; Russian Academy of Sciences [24.29, 24.31, III.9.5, 43]; SFU [101]; Russian Ministry of Education and Science [1792]
Место публикации : J. Opt. Soc. Am. B: Optical Society of America, 2014. - Vol. 31, Is. 12. - P.2981-2989. - ISSN 0740-3224, DOI 10.1364/JOSAB.31.002981. - ISSN 1520-8540
Примечания : Cited References: 39. - This research was supported in part by the U.S. National Science Foundation under Grant DMS1216970; by the Russian Academy of Sciences under Grants 24.29, 24.31, III.9.5, 43, and SFU (101); and by the Russian Ministry of Education and Science under Contract 1792.
Предметные рубрики: DISPERSION-RELATIONS
MODES
SCATTERING
ARRAYS
GUIDES
LIGHT
GAIN
Аннотация: We study numerically the discrete dispersion relations and waveguiding properties of relatively short linear chains of spherical and spheroidal silver nanoparticles. Simulations are based on the Drude model for the dielectric permittivity of metal and on the dipole approximation for the electromagnetic interaction of particles. We also simulate the dynamics of femtosecond optical pulse propagation along such chains. In the case that we consider (10 particles per chain), reflections from the chain terminals play a significant detrimental role. We show that dissipative traps can be used to reduce the effects of reflections. We also show that chains composed of oblate spheroids with sufficiently small aspect ratio (nanodisks) have better waveguiding properties when compared to chains made of particles with other spheroidal shapes. This includes a slower rate of decay, larger group velocity, and larger bandwidth.
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9.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Rasskazov I. L., Karpov S. V., Markel V. V.
Заглавие : Surface plasmon polaritons in linear chains of silver nanospheroids
Коллективы : Edition of the International Conference Series on Laser-light and Interactions with Particles (10; 2014 ; Aug. ; 25-29; Marseille, France)
Место публикации : 10th Edition of the International Conference Series on Laser-light and Interactions with Particles (LIP-2014): Book of extended abstracts. - 2014. - P.6.1-6.3
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Taroev V. K., Kashaev A. A., Malcherek T., Goettlicher J., Kaneva E. V., Vasiljev A. D., Suvorova L. F., Suvorova D. S., Tauson V. L.
Заглавие : Crystal structures of new potassium silicates and aluminosilicates of Sm, Tb, Gd, and Yb and their relation to the armstrongite (CaZr(Si6O15)·3H2O) structure
Коллективы : Russian Fund of Basic Research [10-05-00344-a]
Место публикации : J. Solid State Chem. - 2015. - Vol. 227. - P.196-203. - ISSN 0022, DOI 10.1016/j.jssc.2015.03.004. - ISSN 1095726X(eISSN)
Примечания : Cited References:27. - We appreciate the financial support by the Russian Fund of Basic Research under grant 10-05-00344-a. We thank the two anonymous reviewers for their helpful comments and suggestions and Ms. Schroeder (KIT-PKM) for improving the English of the manuscript.
Предметные рубрики: BOND-VALENCE PARAMETERS
CHAINS
SYSTEM
Ключевые слова (''Своб.индексиров.''): hydrothermal synthesis--ree-potassium silicates--x-ray diffraction--crystal structure refinement
Аннотация: Silicates of composition K7.81Sm3Si12O32(OH)0.81·0.77H2O and K7Tb3Si12O32·1.36H2O, with the space group P 1 ¯ and unit cell parameters of a=6.9218(3), b=11.4653(4), c=11.6215(4) Å, α=88.063(3)°, β=88.449(3)°, γ=79.266(3)° and a=6.872(3), b=11.440(5), c=11.542(6) Å, α=88.19(4)°, β=88.86(4)°, γ=79.65(4)°, respectively, were synthesized under hydrothermal conditions. Both crystal structures were determined from twinned crystals, and can be idealized to a composition of K7Ln3Si12O32 (KOH)x(H2O)(2−x) (Ln=Sm, Tb), which is closely related to K8Nd3Si12O32(OH). Crystals of the aluminosilicates K2GdAlSi4O12·0.25H2O and K2SmAlSi4O12·0.375H2O prepared by the same method possess monoclinic symmetry with the space group C2/c. The corresponding unit cell parameters are: a=26.67(1), b=7.294(3), c=14.835(6) Å, β=123.44(3)°; and a=26.7406(9), b=7.3288(2), c=14.8498 (6) Å, β=123.514(1)°, respectively. A new type of silicate anion that forms tubes was detected in the K4Yb2Si8O21 structure. K4Yb2Si8O21 is of monoclinic symmetry with the space group C2/c. The unit cell parameters are: a=17.440(2), b=11.786(1), c=12.802 (2) Å, and β=130.902(1)°. The structure is a mixed framework of tubes formed by silica-oxygen tetrahedra connected by pairs of edge sharing Yb-octahedra. The relation of the silicate layers and frameworks encountered in these compounds to the armstrongite silicate framework is discussed.
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Rasskazov I. L., Gerasimov V. S., Karpov S. V., Panasyuk G. Y., Markel V. A.
Заглавие : Propagation of surface plasmon polaritons in chains of non-spherical nanoparticles: the influence of the dielectric substrate
Коллективы : "Days on diffraction", International conference, Санкт-Петербургское отделение Института математики им. В. А. Стеклова, Санкт-Петербургский государственный университет, Euler International Mathematical Institute, Российский фонд фундаментальных исследований
Место публикации : Annual Int. Conf. "Days on Diffraction": [book of abstracts]. - 2015. - P.166-167
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12.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Rasskazov I. L., Karpov S. V., Panasyuk G. Y., Markel V. A.
Заглавие : Controllable propagation of surface plasmon polaritons in chains of non-spherical nanoparticles on dielectric substrate
Коллективы : Electromagnetic and Light Scattering Conference
Место публикации : Electromagnetic & Light Scattering XV : abstracts. - Leipzig, 2015. - Ст.88
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rasskazov I. L., Karpov S. V., Panasyuk G. Y., Markel V. A.
Заглавие : Overcoming the adverse effects of substrate on the waveguiding properties of plasmonic nanoparticle chains
Место публикации : J. Appl. Phys.: American Institute of Physics, 2016. - Vol. 119, Is. 4. - Ст.043101. - ISSN 00218979 (ISSN), DOI 10.1063/1.4940415
Примечания : Cited References: 43. - This work has been carried out thanks to the support of the A*MIDEX project (No. ANR-11-IDEX-0001-02) funded by the “Investissements d'Avenir” French Government program, managed by the French National Research Agency (ANR) and was also supported in part by the U.S. National Science Foundation under Grant No. DMS1216970 and by the Ministry of Education and Science of the Russian Federation under Contract No. 1792.
Предметные рубрики: LINEAR-CHAINS
DISPERSION-RELATIONS
ARRAYS
RESONANCES
GUIDES
NANOSPHERES
MODES
FIELD
POLARITONS
PARTICLES
Аннотация: We have studied numerically the propagation of surface plasmon polaritons (SPPs) in linear periodic chains of plasmonic nanoparticles of different shapes. The chains are deposited on top of a thick dielectric substrate. While in many commonly considered cases the substrate tends to suppress the SPP propagation, we have found that this adverse effect is practically absent in the case when the nanoparticles have the shape of oblate spheroids with sufficiently small aspect ratio (e.g., nanodisks) whose axes of symmetry coincide with the axis of the chain. © 2016 AIP Publishing LLC.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrakovskii G. A., Bezmaternykh L. N., Bayukov O. A., Popov M. A., Schefer J., Neidermayer C., Aleshkevich P., Szymczak R.
Заглавие : Magnetic structure and magnetic excitations in the two-dimensional spin system of the Cu3B2O6 compound
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 49, Is. 7. - P1315-1320. - ISSN 1063-7834, DOI 10.1134/S1063783407070207
Примечания : Cited References: 21
Предметные рубрики: LONG-RANGE ORDER
HEISENBERG-MODEL
GROUND-STATE
GAP
ANTIFERROMAGNET
SRCU2(BO3)(2)
CUGEO3
CHAINS
CAV4O9
Аннотация: This paper reports on the results of measurements of the magnetic susceptibility, heat capacity, neutron scattering, muon spin relaxation, and electron paramagnetic resonance in Cu3B2O6 for the study of the ground state of the spin system of this compound. The results obtained suggest that, at a temperature of 10 K, the spin subsystem of the crystal, which consists of single spins and clusters of pairs and fours of spins interacting with one another, undergoes a transition to a state representing a superposition of the singlet (for clusters) and magnetically ordered (for single spins) states.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev A. D., Bayukov O. A., Vasil'ev A. D., Velikanov D. A., Ivanova N. B., Kazak N. V., Ovchinnikov S. G., Abd-Elmeguid M. M., Rudenko V. V.
Заглавие : Magnetic and electrical properties of Fe1.91V0.09BO4 warwickite
Разночтения заглавия :авие SCOPUS: Magnetic and electrical properties of Fe1.91V 0.09BO4 warwickite
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 97, Is. 5. - P989-995. - ISSN 1063-7761, DOI 10.1134/1.1633954
Примечания : Cited References: 22. - This study was supported in part by the Russian Foundation for Basic Research (project no. 03-02-16286) and by the Federal Program “Integration” (project no. B0017)
Предметные рубрики: ELECTRONIC-STRUCTURE
CRYSTAL-STRUCTURE
FE2OBO3
CHAINS
FE2BO4
FEBO3
Ключевые слова (''Своб.индексиров.''): electric conductivity--magnetic variables measurement--magnetization--single crystals--hopping conductivity--warwickite--iron compounds
Аннотация: We have performed a complex investigation of the structure and the magnetic and electrical properties of a warwickite single crystal with the composition Fe1.91V0.09BO4 . The results of Mossbauer measurements at T = 300 K indicate that there exist "localized" (Fe2+, Fe3+) and "delocalized" (Fe2.5+) states distributed over two crystallographically nonequivalent positions. The results of magnetic measurements show that warwickite is a P-type ferrimagnet below T = 130 K. The material exhibits hopping conductivity involving strongly interacting electrons. The experimental data are analyzed in comparison to the properties of the initial (unsubstituted) Fe2BO4 warwickite. The entire body of data on the electric conductivity and magnetization are interpreted on a qualitative basis. (C) 2003 MAIK "Nauka / Interperiodica".
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Two-particle spin-singlet excitations in coupled spin-1/2 antiferromagnetic alternating chains
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2001. - Vol. 13, Is. 14. - P.3403-3410. - ISSN 0953-8984, DOI 10.1088/0953-8984/13/14/313
Примечания : Cited References: 14
Предметные рубрики: MAGNETIC-PROPERTIES
LIGHT-SCATTERING
CUGEO3
S=1/2
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--approximation theory--chemical bonds--electron transport properties--monte carlo methods--particles (particulate matter)--quantum theory--thermal effects--antiferromagnetic alternating chains--excitation spectrum--interchain exchange--mean-field approximation--quantum monte carlo method--singlet gaps--spin-singlet excitations--energy gap
Аннотация: The spectrum of the two-particle spin-singlet (DeltaS(z) = 0, +/-1) excitations of a weakly coupled antiferromagnetic spin-1/2 alternating (J(1) +/- delta) chain is calculated using a mean-field approximation for the interchain exchange (J(2)) by the quantum Monte Carlo method. The bandwidth change of these excitations, the mass gaps in the singlet-singlet excitation spectrum, the top boundaries of the bands and the velocities of these excitations are estimated as functions of the alternating bond delta. The temperatures at which the singlet gaps close are determined.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Roessli B., Staub U., Amato A., Herlach D., Pattison P., Sablina K. A., Petrakovskii G. A.
Заглавие : Magnetic phase transitions in the double spin-chains compound LiCu2O2
Место публикации : Physica B. - 2001. - Vol. 296, Is. 4. - P.306-311. - ISSN 0921-4526, DOI 10.1016/S0921-4526(00)00574-3
Примечания : Cited References: 17
Предметные рубрики: ORDERED MOMENT
COPPER
CRYSTAL
LI2CUO2
Ключевые слова (''Своб.индексиров.''): muon-spin rotation--spin ladder--magnetic ordering--licu2o2--crystal structure--lithium compounds--magnetic anisotropy--magnetic field effects--magnetic relaxation--magnetization--order disorder transitions--specific heat of solids--x ray diffraction analysis--anisotropic line broadening--muon spin rotation--spin ladder--antiferromagnetic materials
Аннотация: We report high-resolution X-ray diffraction, muon-spin-rotation spectroscopic and specific heat measurements in the double spin-chains compound LiCu2O2. The X-ray diffraction results show that the crystal structure of LiCu2O2 is orthorhombic down to T = 10 K. Anisotropic line-broadening of the diffraction peaks is observed, indicating disorder along the spin chains. Muon-spin relaxation and specific heat measurements show that LiCu2O2 undergoes a phase transition to a magnetic ordered state at T-1 similar to 24 K. The specific heat data exhibits a second lambda -like peak at T-2 similar to 32.5 K, which increases with increasing magnetic field in a similar way to that found in spin-ladder compounds. (C) 2001 Elsevier Science B.V. All rights reserved.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Static and dynamic magnetic properties of coupled spin-1/2 antiferromagnetic chains
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2000. - Vol. 12, Is. 37. - P.8191-8207. - ISSN 0953-8984, DOI 10.1088/0953-8984/12/37/316
Примечания : Cited References: 21
Предметные рубрики: ONE-DIMENSIONAL ANTIFERROMAGNETS
SYSTEMS
SUSCEPTIBILITY
EXCITATIONS
SR2CUO3
CA2CUO3
KCUF3
Ключевые слова (''Своб.индексиров.''): computational methods--copper compounds--correlation methods--functions--magnetic field effects--magnetic properties--magnetization--monte carlo methods--quantum theory--specific heat--thermal effects--excitation spectroscopy--interchain coupling--intrachain couplings--mean-field approximation--spin-spin correlation function--spinons--antiferromagnetic materials
Аннотация: Calculations of the thermodynamic quantities, and the spectra of spinons, triplet excitations, and two-particle spin-singlet (Delta S-z = 0, +/- 1) excitations for a weakly coupled antiferromagnetic S = 1/2 spin chain are made using a mean-field approximation for the interchain couplings (J(2)) by the quantum Monte Carlo method. The mass gaps in these excitation spectra are estimated as functions of the interchain coupling. The critical held H-c, and the temperatures at which the spinon and singlet gaps close (T-1 and T-2, respectively) are obtained. Some peculiarities of the staggered magnetization, the specific heat, and the spin-spin correlation function are found at T-1 = 0.9J(2), T-2 = 1.5J(2), H-c = 3.8J(2), as determined by linear function fitting for J(2)/J(1) 0.15 The intrachain and interchain couplings, and the staggered magnetization for KCuF3, Sr2CuO3, and Ca2CuO3 are estimated, and mass gaps are predicted to exist in the spectra of the spinons and the singlet two-particle excitations.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Quantum Monte Carlo investigation of the magnetic properties of weakly interacting antiferromagnetic chains with an alternating exchange interaction with spin S=1/2
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2000. - Vol. 90, Is. 1. - P194-201. - ISSN 1063-7761, DOI 10.1134/1.559075
Примечания : Cited References: 35
Предметные рубрики: PEIERLS COMPOUND CUGEO3
MAGNON DISPERSION
BI2CUO4
EXCITATIONS
RESONANCE
SYSTEMS
SCATTERING
DYNAMICS
NEUTRON
PHASE
Аннотация: An approximation dependence of the spontaneous magnetic moment at a site, sigma/sigma(0) - 1 = 0.71(6)delta(2.5(2)), and the antiferromagnet-singlet state phase boundary, J(2)/J(1) = 0.52(3)delta, are determined by the quantum Monte Carlo method in the self-consistent sublattice molecular field approximation for weakly interacting (J(2)) antiferromagnetic chains with spin S = 1/2 and alternating exchange interaction (J(1) +/- delta). The Neel temperature and a number of critical temperatures which could be related with the filling energy of two singlets (Delta S-z = 0) and one triplet (Delta S-z= 1) spin bands, each of which is split by the sublattice field (h(x,y)not equal h(z)) into two subbands, are determined on the basis of the computed correlation radii of the two- and four-spin correlation function, the squared total spin (S-z)(2) with respect to the longitudinal components, the dimerization parameter, and the correlation functions between the nearest neighbors with respect to longitudinal and transverse spin components. On the basis of the Monte Carlo calculations, the critical temperatures and possible energy gaps at the band center are determined for the antiferromagnets CuWO4 and Bi2CuO4 and for the singlet compounds (VO)(2)P2O7 and CuGeO3 , agreeing satisfactorily with existing results, and new effects are also predicted. (C) 2000 MAIK "Nauka / Interperiodica".
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Petrakovskii G. A.
Заглавие : Investigation of the magnetic properties of chains with alternating ferro- and antiferromagnetic exchange interactions in the Heisenberg model with spin S=1/2
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 1999. - Vol. 41, Is. 9. - P1511-1512. - ISSN 1063-7834, DOI 10.1134/1.1131042
Примечания : Cited References: 11
Предметные рубрики: HALDANE-GAP
SYSTEMS
Аннотация: The quantum Monte Carlo method is used to calculate the susceptibility and pairwise spin-spin correlation functions of chains with alternating ferro (K)- and antiferromagnetic (J)-exchange interactions within the Heisenberg model with spin S=1/2. From the susceptibility, the energy gap between the ground state and excited triplet states is determined for arbitrary ratios K/J. The value of the gap coincides with the Haldane gap for spin S=1 when K/J 1.25. (C) 1999 American Institute of Physics. [S1063-7834(99)02409-0].
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