Spin dynamics of Sr14Cu(24)O(41) two-leg ladder studied by raman spectroscopy - art. no. 197202

The two-magnon (2M) excitation at 3000 cm(-1) in Sr14Cu24O41 two-leg ladder is studied by Raman scattering. A slight anisotropy of the superexchange c oupling J(perpendicular to)/J(parallel to) approximate to 0.8 with J(parall el to) = 110 +/- 20 meV is proposed from the analysis of the magnetic scatt ering. The resonant coupling across the charge transfer gap increases the 2 M intensity by orders of magnitude. The anisotropy of Raman scattering is d ependent upon the excitation energy. The 2M relaxation is found to be corre lated with the temperature dependent electronic Raman continuum at low freq uencies.