Труды сотрудников института физики

/ V. V. Val'kov, M. S. Shustin // JETP Letters. - 2014. - Vol. 100, Is. 7. - P. 455-462, DOI 10.1134/S0021364014190138. - Cited References: 28. - This work was supported by the Russian Foundation for Basic Research, project nos. 12-02-31130, 13-02-00523, and 13-02-98013. . - ISSN 0021-3640. - ISSN 1090-6487РУБ Physics, Multidisciplinary

Аннотация: TThe excitation spectrum of a catena-[FeII(ClO4)2{FeIII(bpca)2}]ClO4 anisotropic 1D magnet with alternating high-spin and low-spin iron ions has been calculated with the use of the diagrammatic technique for Hubbard operators. This has allowed establishing conformity with the Ising model, for which the magnetic susceptibility has been calculated by the transfer-matrix method. The introduction of a statistical ensemble taking into account the presence of chains with different lengths and iron ions with different spins has allowed describing the modification of the magnetic susceptibility under optical irradiation.

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Держатели документа:
Russian Acad Sci, Siberian Branch, Kirensky Inst Phys, Krasnoyarsk 660036, Russia
Siberian Fed Univ, Krasnoyarsk 660041, Russia

Доп.точки доступа:
Shustin, M. S.; Шустин, Максим Сергеевич; Вальков, Валерий Владимирович; Russian Foundation for Basic Research [12-02-31130, 13-02-00523, 13-02-98013]

/ V. V. Val'kov, M. S. Shustin // J. Exp. Theor. Phys. - 2015. - Vol. 121, Is. 5. - P. 860-877, DOI 10.1134/S1063776115110175. - Cited References:46. - This work was supported by the Russian Foundation for Basic Research, project nos. 13-02-00523, 14-02-31237, and 15-42-04372 . - ISSN 1063-7761. - ISSN 1090-6509РУБ Physics, Multidisciplinary

Аннотация: The dispersion equation of a strongly anisotropic one-dimensional magnet catena-[FeII(ClO4)2{FeIII(bpca)2}]ClO4 containing alternating high-spin (HS) (S = 2) and low-spin (LS) (S = 1/2) iron ions is obtained by the diagram technique for Hubbard operators. The analysis of this equation yields six branches in the excitation spectrum of this magnet. It is important that the crystal field for ions with spin S = 2 is described by the Hamiltonian of single-ion easy-plane anisotropy, whose orientation is changed by 90° when passing from one HS iron ion to another. The U(N) transformation technique in the atomic representation is applied to diagonalize a single-ion Hamiltonian with a large number of levels. It is shown that the modulation of the orientation of easy magnetization planes leads to a model of a ferrimagnet with easy-axis anisotropy and to the formation of energy spectrum with a large gap. For HS iron ions, a decrease in the mean value of the spin projection due to quantum fluctuations is calculated. The analysis of the specific features of the spectrum of elementary excitations allows one to establish a correspondence to a generalized Ising model for which the magnetic susceptibility is calculated in a wide range of temperatures by the transfer-matrix method. The introduction of a statistical ensemble that takes into account the presence of chains of different lengths and the presence of iron ions with different spins allows one to describe the experimentally observed modification of the magnetic susceptibility of the magnet under optical irradiation.

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Scopus,
WOS,
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Держатели документа:
Russian Acad Sci, Siberian Branch, Kirenskii Inst Phys, Krasnoyarsk 660036, Russia.
Siberian Fed Univ, Krasnoyarsk 660041, Russia.

Доп.точки доступа:
Shustin, M. S.; Шустин, Максим Сергеевич; Вальков, Валерий Владимирович; Russian Foundation for Basic Research [13-02-00523, 14-02-31237, 15-42-04372]