Overview

This program emphasizes materials synthesis and processing, advanced characterizations and studies of materials properties, all aimed at a fundamental understanding of materials that have potential for applications. Currently the program concentrates on complex oxides with two connected goals:

• Understanding the complex interrelationship between charge and spin degrees of freedom and with crystal structure.
• Understanding the proximity interactions which occur when an oxide shares a common boundary with a metal or other oxides.

Specific examples include:

• High-temperature superconductors, with a growing interest on the role of grain boundaries and their effects on transport properties.
• Colossal magnetoresistance in naturally layered manganities.

This activity studies the fundamental science of oxides, a large class of materials with a wide range of physical properties and potential uses. Currently, interests emphasize high-temperature superconductors and colossal magnetoresistive oxides. Two interconnected goals of this activity are: (1) to understand the complex relationship of the charge and spin degrees of freedom and the crystal structure; and (2) to understand proximity interactions that occur when an oxide shares a common boundary with a metal or another oxides. For the first of these, the highest quality single crystals are grown, characterized and their physical properties measured. Collaborations are in place with neutron scattering, magnetic properties and theory groups. For the second goal, research in oxide grain boundaries is supplemented with a new activity on deposited oxides, including multilayers, superlattices and graded coatings with an emphasis on epitaxial growth. Connections are made to practical applications and with theoretical modeling studies. Another effort is in reacted oxide surface layers (oxide scales) as part of the DOE-BES Center of Excellence in Synthesis and processing. It also emphasizes model systems (e.g., single crystal substrates). Considerable feedback and crossfertilization of ideas between these areas and with external collaborators are at the core of the group's activities. Samples synthesized and investigated include single crystals, melt-textured ingots, epitaxial films, thin-film and bulk bicrystals, polycrystalline ceramics and thermally-grown oxide scales.