Dynamics of spin fluctuations in Lanthanum Cuprate.
01 January 1988
Raman scattering studies of La sub 2 Cu0 sub 4 have revealed a high frequency component (-3000 cm sup (-1)) which we interpret as due to scattering by magnon pairs. Comparison of the spectra with those of K sub 2 NiF sub 4 leads to a value of J-1000 cm sup (-1) for the exchange interaction. The 2D nature of the fluctuations suggested by earlier neutron scattering work is indicated by the insensitivity of the spectra to temperature as well as to departures from stoichiometry which strongly influence the 3D ordering temperature Tw.