title: Cooperative Jahn-Teller phase transition in LaMnO3 studied by X-ray absorption spectroscopy.
abstract: The local structure of LaMnO3 across the Jahn-Teller (JT) transition at T(JT)=750 K was studied by means of x-ray absorption near edge structure and extended x-ray absorption fine structure at the Mn K-edge. Our results indicate a similar electronic local structure for Mn atoms above and below T(JT) and a dynamical tetragonal JT distortion of MnO6 octahedra above T(JT). The structural transition is originated by the ordering of tetragonally distorted octahedra. The entropy content of the transition is analyzed within the framework of the three-state Potts model with nearest neighbor antiferrodistortive coupling.
authors.affiliation: Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas y Universidad de Zaragoza, 50009 Zaragoza, Spain.
authors.forename: M C
authors.initials: MC
authors.lastname: Sánchez
authors.forename: G
authors.initials: G
authors.lastname: Subías
authors.forename: J
authors.initials: J
authors.lastname: García
authors.forename: J
authors.initials: J
authors.lastname: Blasco