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Elementary excitations, exchange interaction and spin-Peierls transition in CuGeO3

Czechoslovak Journal of Physics volume 46, pages 3239–3246 (1996)Cite this article

Abstract

The microscopic description of the spin-Peierls transition in pure and doped CuGeO3 is developed taking into account realistic details of crystal structure. It it shown that the presence of side-groups (here Ge) strongly influences superexchange along Cu−O−Cu path, making it antiferromagnetic. Nearest-neighbour and next-nearest neighbour exchange constantsJ nn andJ nnn are calculated. Si doping effectively segments the CuO2-chains leading toJ nn (Si)≃0 or even slightly ferromagnetic. Strong sensitivity of the exchange constants to Cu−O−Cu and (Cu−O−Cu)−Ge angles may be responsible for the spin-Peierls transition itself (“bond-bending mechanism” of the transition). The nature of excitations in the isolated and coupled spin-Peierls chains is studied and it is shown that topological excitations (solitons) play crucial role. Such soltons appear in particular in doped systems (Cu1−x Zn x GeO3, CuGe1−x Si x O3) which can explain theT SP (x) phase diagram.

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Authors and Affiliations

  1. Groningen University, Nijenborgh 4, 9747 AG, Groningen, the Netherlands

    D. Khomskii, W. Geertsma & M. Mostovoy

  2. P. N. Lebedev Physical Institute, Leninski prosp. 53, Moscow, Russia

    D. Khomskii

  3. G. I. Budker Institute of Nuclear Physics, 630090, Novosibirsk, Russia

    M. Mostovoy

Authors
  1. D. Khomskii
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  2. W. Geertsma
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  3. M. Mostovoy
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Khomskii, D., Geertsma, W. & Mostovoy, M. Elementary excitations, exchange interaction and spin-Peierls transition in CuGeO3 . Czech J Phys 46, 3239–3246 (1996). https://doi.org/10.1007/BF02548136

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  • DOI: https://doi.org/10.1007/BF02548136

Keywords

  • Soliton
  • Spin Chain
  • Exchange Constant
  • Elementary Excitation
  • Strong Coupling Limit