TITLE: "Experimental Investigations of the Dynamics of Flux vortices in High Transition Temperature Superconductors"

SPEAKER: Professor Carmen Almasan,

The high transition temperature superconductors represent a new class of materials which have extraordinary superconducting and magnetic properties and great potential for a wide-range of technological applications. For example, these superconductors are characterized by unusually low flux pinning energies. As a result, the flux vortices, present in a superconductor placed in a magnetic field, move easily in the presence of a current, giving rise to dissipation of energy. Hence, the superconductor loses one of its main characteristics, i.e., zero resistance. On the other hand, this enhanced flux flow characteristic makes the high temperature superconductors especially attractive for investigating vortex dynamics. In this talk, I will present experimental studies of both transport and magnetic measurements which probe the magnetic flux matter and its dynamics. The understanding of the dynamics of the vortex matter is two fold. First, it could provide insights into the basic phenomena of high tempera ture superconductivity by addressing issues such as the temperature and magnetic field range over which these materials are really superconducting (zero resistance), and the nature and mechanism of pinning of flux lines. Second, it could provide ways to improve the magnetic quality of the presently known materials by enhancing flux pinning in a controllable manner.