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  Senff, D.; Schumann, O.; Benomar, M.; Kriener, M.; Lorenz, T.; Sidis, Y.; Habicht, K.; Link, P.; Braden, M.: Melting of magnetic correlations in charge-orbital ordered La_1/2Sr_3/2MnO₄ : Competition of ferromagnetic and antiferromagnetic states. Physical Review B 77 (2008), p. 184413/1-14

10.1103/PhysRevB.77.184413
Open Access Version

Abstract:
The magnetic correlations in the charge and orbital ordered manganite La1/2Sr3/2MnO4 have been studied by elastic and inelastic neutron scattering techniques. Out of the well-defined charge exchange
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, La1/2Sr3/2MnO4 exhibits a dispersion of ferromagnetic correlations, which remarkably resembles the magnon dispersion in ferromagnetically ordered metallic perovskite manganites.