This project involves collaboration between an experimentalist at Case Western University and a theorist at Iowa State University. The research involves the use of high sensitivity equilibrium torque measurements of high-Tc materials. The theoretical goal of the project is to determine how the behavior of the torque in such materials is influenced by thermal fluctuations. The experimental thrust is focused on three areas: the flux-lattice melting transition in yttrium-barium-copper-oxide materials, the magnetic field dependence of this transition, and the determination of the symmetry of the superconducting ground state in this material. These results should lead to a deeper understanding of the behavior of high-Tc materials in a magnetic field. %%% High temperature superconductors are being widely studied, in part because of their potential for carrying large electrical currents without the energy losses found in ordinary conductors such as copper and aluminum. However, the very large currents in the superconductors generate very large magnetic fields which react back on the superconductors and eventually destroy the superconducting state. Thus the behavior of superconductors in magnetic fields is a fundamental issue in high-Tc materials research. This project involves both a theorist and experimentalist in an effective collaboration which is focused on studying the forces experience by a superconductor in a magnetic field. This magnetic torque measurement apparatus is unique in the US and is providing important fundamental information that is also useful in technological applications.
