Magnetic excitations in charge-ordered Nd0.5Ca0.5MnO3: A Brillouin scattering study

Brillouin scattering studies on single crystals of a charge-ordered mangani te, Nd0.5Ca0.5MnO3, have been carried out for the first time. The spectra s how two modes at similar to 27 GHz (B-mode) and 60 GHz (S-mode). The B-mode frequency and intensity from 300 K to 27 K, covering both the charge order ing transition at 250 K and the antiferromagnetic transition, at 170 K, exa ctly follow the same temperature dependence as the d.c. magnetic susceptibi lity. The B-mode is associated With bulk magnetic excitations and the S-mod e with surface magnetic excitations of the manganite with ferromagnetic cor relations. The study is strongly indicative of the presence of ferromagneti c inhomogeneities in the charge-ordered as well as antiferromagnetic phases .