High Temperature Neutron Diffraction Study of the La1.4Sr1.6mn2o7   Bilayered Manganite
  In this paper we present the results of a high temperature (300 K<T<800 K) neutron powder diffraction study of the La1.4Sr1.6Mn2O7 bilayered manganite. An unusual trend of the <Mn-Oapical>/Mn-Oequatorial parameter was found: it first decreases up to 500 K and then increases up to the highest T measured. At the same time, a significant shortening of the apical Mn-O(2) bond is observed in the range where the J-T distortion is reduced. The overall data gained by this study may suggest a shift of electronic density from axial to planar eg orbitals with T. This trend is explained considering of the presence of short range magnetic interaction well above TC. 
Lorenzo Malavasi, Gaetano Chiodelli, Hakan Rundlof, Cristina Tealdi,   and Giorgio Flor