****Technical Abstract**** This award supports experimental low-temperature physics research at an undergraduate institution. The scaling analysis of voltage vs. current curves has been an invaluable tool in the study of the normal-superconducting phase transition. However, recent work has shown that the conventional application of this tool is too flexible to uniquely determine the critical parameters, and that extrinsic effects can obscure or destroy the phase transition. With these caveats known, we have successfully applied this technique to study the hole-doped cuprate YBa2Cu3O7 and the electron-doped cuprate Pr2-xCexCuO4. This project will use the same technique to examine the phase transition in the new iron pnictide-122 superconductors (SrFe2As2 and BaFe2As2) both in a magnetic field and in zero magnetic field. This work will lead to an understanding of the model that governs the phase transition in this material and the differences and similarities of the phase transition between iron pnictide superconductors and other superconductors. This project will also train undergraduate students in experimental and low-temperature physics in preparation for graduate work or industry careers. In addition, to encourage broader education in science, this project will contribute to an existing outreach program with local public schools and submit video demonstrations to YouTube.
This award supports experimental low-temperature physics research at an undergraduate institution. "High-Temperature" superconductors, discovered more than a quarter of a century ago, still hold great promise and great challenges. The promise lies in the hope of eventually making superconductors with much higher transition temperatures, and the challenges lie in the fact that we do not, even 25 years later, fully understand how or why these materials superconduct. Superconductors made from iron and arsenic, discovered in 2008, are the latest in an array of unusual materials to display superconductivity. This individual investigator award supports a project that will study how iron- and arsenic-based materials become superconducting, comparing them to copper-oxygen based superconductors and conventional, single element superconductors, all in the hopes of understanding the underlying mechanism that creates superconductivity in these materials. The proposed studies will add to the knowledge of high-temperature superconductors and help fulfill the promise of attaining higher transition temperatures. This project will also train undergraduate students in state-of-the-art sample growth, characterization, and measurement techniques. This project will also contribute to broader educational goals by fostering science outreach to local schools and promoting the research via online video demonstrations.
