9701735 Shelton This experimental research program focuses on distinct classes of materials that display competing collective spin states. There is an emphasis on materials that have an inter-relationship among their crystallographic properties and their collective behaviors that are manifested at room temperature and below. To determine the intrinsic physical properties, the research stresses experiments on high-quality single crystals. Two families form the core of these studies; namely, spin Peierls and spin gap compounds such as CuGeO3, CaV4O9 and derivative compounds and colossal magneto-resistive compounds such as (La,Ca,Bi)MnO3, Eu14MnSb11 and related materials. To ensure consistency and uniformity in interpreting the experimental results, a great variety of complementary experiments will be performed on the same single crystals. %%% This experimental research program focuses on two families of materials that show great promise for technological applications and are associated with distinctive magnetic properties; namely, spin gap and colossal magneto-resistive (CMR) compounds. Some examples are CuGeO3, CaV4O9, (La,Bi)MnO3, and Eu14MnSb14. These materials are attracting great attention from the magnetic recording industry. Due to the intrinsic complexity of these multi-component materials, great emphasis is placed on using the highest quality crystals in this study. Goals with practical aspects include: elemental substitutions to optimize the performance characteristics; discovery of new materials to raise the critical operating temperatures of the CMR compounds. ***
