MATERIALS SCIENCE COLLOQUIUM

Refreshments will be served at 10:45 a.m.

ABSTRACT: The discovery of high critical temperature superconductivity in complex metal cuprate and pnictide compounds is one of the most remarkable events in modern science. It is a major breakthrough in materials synthesis and in developing new concepts, compounds and technologies in solid state physics and materials science. It also underscores the significance of new materials with novel properties in revolutionizing entire scientific and technological fields. While the bulk of efforts are aimed at establishing a satisfactory theoretical model of the electronic structure in order to understand the formation of the superconducting phase, the ability to design and synthesize superconductors or to predict their transition temperatures is far less developed and is an objective that seems attainable only in the long term.

A focused materials synthesis program is under way at MSD to discover new electronic materials and investigate their superconducting potential. The classes of compounds under investigation include pnictides, chalcogenides and intermetallics. These systems exhibit either competing interactions or are narrow gap semiconductors. The project pursues a multi-faceted approach that combines the rational design of novel materials with structural and electronic probes. We are creating materials with a high degree of structural and compositional freedom and chemical/electronic complexity with which to investigate (a) density-wave instabilities (spin and charge), and their suppression through chemical doping in order to generate superconductivity that may emerge from phase competition, and (b) how narrow energy band gaps and facile doping properties could lead to a superconducting state. Our work today on the iron pnictide materials and alkali metal iron chalcogenide superconductors and non-superconductors will be presented.