Melting of magnetic correlations in charge-orbital ordered   La(0.5)Sr(1.5)MnO(4) : competition of ferro and antiferromagnetic states
  The magnetic correlations in the charge- and orbital-ordered manganite La(0.5)Sr(1.5)MnO(4) have been studied by elastic and inelastic neutron scattering techniques. Out of the well-defined CE-type magnetic structure with the corresponding magnons a competition between CE-type and ferromagnetic fluctuations develops. Whereas ferromagnetic correlations are fully suppressed by the static CE-type order at low temperature, elastic and inelastic CE-type correlations disappear with the melting of the charge-orbital order at high temperature. In its charge-orbital disordered phase, La(0.5)Sr(1.5)MnO(4) exhibits a dispersion of ferromagnetic correlations which remarkably resembles the magnon dispersion in ferromagnetically ordered metallic perovskite manganites. 
D. Senff, O. Schumann, M. Benomar, M. Kriener, T. Lorenz, Y. Sidis, K.   Habicht, P. Link, and M. Braden