Cooperative Jahn-Teller transition and resonant x-ray scattering in thin film LaMnO3

Abstract

Epitaxial thin films of stoichiometric LaMnO3 were grown on SrTiO3(110) and MgO(110) substrates. The cooperative Jahn-Teller (JT) transition was found to occur at T-JT=573.0 and 670.0 K for films on SrTiO3 and MgO, respectively. Extended x-ray-absorption fine structure, and resonant x-ray scattering intensity of the orthorhombic (100) peaks near the Mn K-edge were measured from low temperatures to above T-JT. We demonstrate that the integrated intensity of the resonant x-ray peak is proportional to the 3/2 power of the orthorhombic lattice strain as well as local bond orthorhombicity at all temperatures for both films. This proves that the band effect associated with the JT distortion accounts for the Mn K-edge resonant scattering in LaMnO3.