Does the Heisenberg model describe the multimagnon spin dynamics in antiferromagnetic CuO layers?

Citation
J. Lorenzana et al., Does the Heisenberg model describe the multimagnon spin dynamics in antiferromagnetic CuO layers?, PHYS REV L, 83(24), 1999, pp. 5122-5125
Citations number
29
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW LETTERS
ISSN journal
00319007 → ACNP
Volume
83
Issue
24
Year of publication
1999
Pages
5122 - 5125
Database
ISI
SICI code
0031-9007(199912)83:24<5122:DTHMDT>2.0.ZU;2-B
Abstract
We compute the absorption spectrum for multimagnon excitations assisted by phonons in insulating layered cuprates using exact diagonalization in clust ers of up to 32 sites. The resulting line shape is very sensitive to the un derlying magnetic Hamiltonian describing the spin dynamics. For the usual H eisenberg description of undoped Cu-O planes we find, in accordance with ex periment, a two-magnon peak followed by high energy sidebands. However the relative weight of the sidebands is too small to reproduce the experiment. An extended Heisenberg model including a sizable four-site cyclic exchange term is shown to be consistent with the experimental data.