W0316

X-ray and Neutron Scattering Studies of Lattice Effects in Complex Oxides. Sunil Sinha, U. California San Diego/Los Alamos National Laboratory, Branton Campbell*, Ray Osborn, Stefan Rosenkranz, John Mitchell, Dimitri Argyriou**, Lida Vasiliu-Doloc, Oliver Seeck***, Argonne National Laboratory, Jeff Lynn, Natl. Institute of Standards and Technology, * Current Address: Dept. of Physics, Brigham Young Univ. ** Current Address: Hahn-Meitner Institute, Berlin, ***Current Address: IFF, FZ Julich GmbH, Germany.

We shall review what has been learned about the physics of the so-called Colossal Magnetoresistance (CMR) Manganite compounds from recent neutron and synchrotron X-ray scattering studies. A fascinating variety of competing phenomena manifest themselves in these materials such as ferromagnetism, antiferromagnetism, charge and orbital ordering as well as the occurrence of polarons driven by the Jahn-Teller effect. PDF measurements on powder samples as well as diffuse X-ray scattering studies.

On single crystals have revealed directly the formation of Jahn-Teller-driven polarons associated with oxygen displacements around the Mn3+ ions. These collapse below Tc with the onset of double-exchange-driven ferromagnetism, while above Tc they form a polaron-liquid with stripe-like short-range order. These phenomena illustrate the variety of competing interactions which can occur in complex oxide materials. We shall also discuss the similarities with recent results on single crystals of High-Tc superconductors.