Neutron Powder Diffraction Studies of Magnetic Quasi-degenerated Oxides with Competing Degrees of Freedom

Abstract

Neutron powder diffraction has been extensively used during last years to address a wide diversity of problems in the field of Strongly Correlated Oxides. Very rich phase diagrams are a common feature of materials formed by metal-oxygen bonds with seemingly simple structures, originating from strong electron-correlations and involving spin, charge, orbital, and lattice degrees of freedom. Competing energy terms do not always favor conventional itinerant Bloch states, and make possible quasi-degenerate configurations that render these systems prone to self-organization of electrons into superstructures, or nano- and mesoscopic inhomogeneous states, or to offer giant responses. During the last years, our main research activity using neutrons has been focused on the structure-properties relationship of magnetic and electronic oxides with competing degrees of freedom: narrow-band oxides with metal-insulator transitions, materials with colossal magnetoresistance, manganites, half-metallic ferrimagnetic oxides, nickelates, vanadates, cobaltites, charge and orbital ordered phases, exotic phases in degenerated magnetic materials, etc.