Europhys. Lett, 48 (6), pp. 648-654 (1999)
Electron-phonon and spin-phonon coupling in
Charge fluctuations effects
E. Ya. Sherman,
M. Fischer, P. Lemmens
P. H. M. van Loosdrecht and G. Güntherodt
II. Physikalisches Institut, RWTH-Aachen - 52056 Aachen, Germany
(received 16 March 1999; accepted in final form 15 October 1999)
PACS. 63.20Kr - Phonon-electron and phonon-phonon interactions.
PACS. 75.30Et - Exchange and superexchange interactions.
PACS. 78.30-j - Infrared and Raman spectra.
We show that the asymmetric crystal environment of the V site in the ladder compound NaV2O5 leads to a strong coupling of vanadium 3d electrons to phonons. This coupling causes fluctuations of the charge on the V ions, and favors a transition to a charge-ordered state at low temperatures. In the low temperature phase the charge fluctuations modulate the spin-spin superexchange interaction, resulting in a strong spin-phonon coupling.
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