MATERIALS SCIENCE AND ENGINEERING SEMINAR Defect Engineering for Magnetic Vortex Pinning in Iron-Pnictide Superconductors for High Magnetic Field Applications By Mitchell Wood Purdue MSE Ph.D. Prelim Exam Part I Advisor- Prof. A. Strachan ABSTRACT Since the discovery of superconductivity in an iron-containing compound in 2008, research into these materials has advanced at a blistering pace, rivaling the cuprate compounds of a few decades ago. Paramagnetic compounds were previously thought to destroy the superconducting state but, with new insight, it is found that the exchange of paramagnetic order offers a strong Cooper pairing mechanism, in contrast to phonon exchange. Advances in this area have brought critical temperatures up to about 50K with the added advantage of high upper critical magnetic fields, up to 100 tesla in some cases. Though the critical temperatures are far below cuprate super-conductors, their low anisotropy crystal structures and possibility for enhancing properties through doping allow for strong pinning of magnetic vortices to yield high critical current densities. In high field applications, such as in particle accelerators or medical imaging, these materials could possibly rival the industry standard Bi2Sr2CaCu2Ox (BSCCO) high temperature superconductor (HTSC), but a detailed understating of the microstructural effects on flux pinning would aid the design and manufacture of better materials. Therefore, what can we use from decades of HTSC research into similar systems to improve the pinning mechanisms in iron based superconductors? Furthermore, can we use the unique Cooper pairing in Fe-HTSC to our advantage when designing these materials for high magnetic field applications? The focus here will be on the capability to engineer pinning landscapes that can allow large currents at high values of magnetic field. Date: October 17, 2013 Time: 2:30 PM. Place: ARMS 3109 Lisa Stacey Secretary/Development Assistant Purdue University School of Materials Engineering 765/494-4100