Raman scattering study of anomalous spin, charge, and lattice dynamics in the charge-ordered phase of Bi1-xCaxMnOs3 (x > 0.5)

We report an inelastic light scattering study of the effects of charge orde ring on the spin, charge, and lattice dynamics of Bi1-xCaxMnO3 (x > 0.5). W e find that charge ordering results in anomalous phonon behavior, such as t he appearance of "activated" modes. More significantly, however, the transi tion to the charge-ordered phase results in the appearance of a quasielasti c scattering response with the symmetry of the spin-chirality operator (T-1 g); this scattering response is thus indicative of magnetic or chiral spin fluctuations in the antiferromagnetic charge-ordered phase.