U.S.-Austria Cooperative Research on Anisotropy In Grain Aligned Superconducting (123)-Compounds

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This award supports collaborative interactions between scientists in the Department of Physics, Iowa State University, led by Professor Douglas K. Finnemore, and Professor Harald W. Weber and colleagues of the Atomic Institute of the Austrian Universities, in Vienna. The two groups have been studying the anisotropy of the magnetic properties and current carrying capacity of high temperature superconductors. Their goal is to develop bulk superconducting materials which will carry a high critical current and thus be suitable for conductor material in large magnets. Their cooperative work plan relies heavily on their complementary expertise and facilities. The Iowa State University group is very experienced in the theory of anisotropic superconductors, in sample preparation for grain oriented materials, in measure- ments of the vortex line energy and in the study of pinning potentials for vortex motion. The Austrian group has great experience with radiation damage in superconductors and highly accurate studies of the fundamental magnetization properties of these highly anisotropic materials The U.S. group at Iowa State University will prepare the grain oriented crystal samples, measure their basic properties and arrange for their irradiation at several U.S. accelerator facilities. The Austrian group will measure the magnetic and structural properties of these materials using different magnetization instruments (including their 17 tesla magnetiza- tion apparatus.) There will also be a thorough study of the damage done by the ion tracks using transmission electron spectroscopy. The development of an understanding of anisotropy effects for flux pinning in high temperature superconductors would have both fundamental and practical implications. Classical superconductors are highly isotropic compared to the high temperature materials, so the experiments proposed here are in a new regime where dimensionality and topology play a more important role. In addition, there is a large payoff for the development of new materials and new processing methods to produce conductors with higher critical current density values. There is at present no satisfactory conductor material for magnetics because the mechanical properties and the transport critical currents are so poor. Thus, any improvement in the critical current carrying capacity of the high temperature bulk superconductors would have a large impact on the availability of new magnets and new shielding materials.