New theory of the spin-peierls transition with special relevance to the experiments on TTFCuBDT
A new theory of the spin-Peierls transition in spin-1/2 Heisenberg chains is developed in which the phonons are treated in a mean field, random phase approximation as in previous work, but in which the relevant response functions of the spins are calculated using the procedure of Luther and Peschel. 7 This gives a much better approximation than the Hartree treatment used before, taking realistically into account the one-dimensional nature and showing the important differences from an XY model.The leading divergences of the spin response should be given exactly by our calculation. We find a new linear dependence of the transition temperature of the spin-phonon coupling constant and an enhancement of the transition temperature and also of the phonon softening above this temperature. Predictions of some other signatures of the transition, such as the specific heat jump to normal specific heat ratio, are not much changed from earlier work, however. New exact results are found at zero temperature.
KeywordsLattice Distortion Random Phase Approximation Magnetic Dipole Moment Heisenberg Chain Phonon Softening
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- 1.Reviewed by L. V. Interrante, this-conference.Google Scholar
- 2.J. C. Bonner and M. E. Fisher, Phys. Rev. A135, 610 (1964).Google Scholar
- 4.E. Pytte, Phys. Rev. B10, 4637 (1974).Google Scholar
- 5.L. N. Bulaevskii, Zh. Eksp. Theor. Fiz. 44, 1008 (1963).Google Scholar
- 7.A. Luther and I. Peschel, Phys. Rev. B12, 3908 (1975).Google Scholar
- 8.L. N. Bulaevskii, Zh. Eksp. Theor. Fiz. 43, 968 (1962).Google Scholar
- 9.J. C. Bonner, H. W. J. Blöte and J. D. Johnson, J. de Phys. (Paris) C6, 710 (1978) and private communication.Google Scholar