Cooperative Jahn-Teller phase transition in LaMnO3 studied by x-ray absorption spectroscopy -: art. no. 045503

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.