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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
E. Pytte, Phys. Rev. B10, 4637 (1974).
L. N. Bulaevskii, A. I. Buzdin, and D. I. Khomskii, Solid State Commun.27, 5 (1978).
M. C. Cross and D. S. Fisher, Phys. Rev. B19, 402 (1979); M. C. Cross, Phys. Rev. B20, 4606 (1979).
J. W. Brayet al., in “Extended Linear Chain Compounds”, ed. J. S. Miller, (Plenum, NY 1985), p. 353.
M. Hase, I. Terasaki, and K. Uchinokura, Phys. Rev. Lett.70, 3651 (1993).
J. E. Leronzoet al., Phys. Rev. B50, 1278 (1994).
H. Winkelmannet al, Phys. Rev. B51, 12884 (1995).
B. Büchnerat al, Phys. Rev. Lett. in press.
M. haseet al, Phys. Rev. Lett.71, 4059 (1993).
J. P. Renardet al, Europhys. Lett.30, 475 (1995).
Y. Sasagoet al, preprint cond-mat/9603185.
L. P. Regnaultet al, Europhys. Lett.32, 579 (1995).
W. Geertsma and D. Khomskii, Phys. Rev. B54 (1996).
G. Castilla, S. Chakravarty and V. J. Emery, Phys. Rev. Lett.75, 1823 (1995).
C. K. Majumdar and D. K. Ghosh, J. Math. Phys.10, 1388, 1899 (1969).
W. Geertsma and D. Khomskii, to be published.
M. Bradenet al, preprint 1996.
B. Büchner, W. Geertsma and D. Khomskii, to be published.
K. Hirotaet al, Phys. Rev. Lett.31, 736 (1994).
A. J. Heeger, S. Kivelson, J. R. Schrieffer, and W. P. Su, Rev. Mod. Phys.60, 781 (1988).
W. P. Su, Solid State Commun.35, 899 (1980).
M. Mostovoy and D. Khomskii, to be published.
M. Mostovoy, M. T. Figge, and J. Knoester, to be published.
The coexistence of the SP and the antiferromagnetic phases was recently treated by H. Fukuyama, T. Tanimoto and M. Saito, J. Phys. Soc. Japan,65, 1182 (1996). Our approach is rather similar, with one important difference: due to the presence of solitons the change of phase by π is allowed in our picture, whereas it is not realized in the solution obtained in the above cited paper.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Khomskii, D., Geertsma, W. & Mostovoy, M. Elementary excitations, exchange interaction and spin-Peierls transition in CuGeO3 . Czech J Phys 46 (Suppl 6), 3239–3246 (1996). https://doi.org/10.1007/BF02548136
Issue Date:
DOI: https://doi.org/10.1007/BF02548136