Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} As a Model System for Fundamental Studies of High Temperature Superconductivity

During the past year, the Principal Investigator (PI) (Z. F. Ren) moved from SUNY-Buffalo to Boston College as an Associate Professor in the Department of Physics to further enhance the future success of this program. Due to the moving and set up of the new laboratory at Boston College, the project was slowed down in some extent. Nevertheless, the PI and his associates have been able to accomplish the following: (1) The upper critical field study has been carried out on the early samples (made when the PI was still with SUNY-Buffalo). Those samples have either high {Tc} (>20K) with single transition or low TC but with double transitions. Therefore, there has no definitive conclusion been drawn yet. (2) X-ray photoemission has been used to study the Tl-2201 thin films. (3) In addition, J. Y. Lao has synthesized the epitaxial thallium-containing 1212 films with critical current density up to 10{sup 6}/cm{sup 2} at 77K and zero magnetic field as part of his Ph.D thesis. The success of this research has enabled us to consider using this material as an alternative for Yba{sub 2}Cu{sub 3}O{sub 7} (YBCO) or TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 9} (Tl-1223) for long length wire development for applications such as transmission cables, motors, generators, etc