Role of Disorder in Determining the Vortex Phase Diagram in High Temperature Superconductors

Western Michigan University, Kalamazoo MI

Investigators

Abstract

This individual investigator award is to a young female professor at Western Michigan University for a project that focuses on manipulating the defect content in high temperature superconductors to resolve the role of disorder in determining the phase diagram of the vortex matter. In these materials, the vortex lattice undergoes a melting transition to a vortex liquid state that occupies a large portion of the phase diagram. This melting transition is a serious impediment to many technological applications because vortices in the liquid state are much more difficult to pin. Any understanding of the role of defects in reducing the vortex liquid regime will help facilitate the technological viability of these materials. The vortex matter phase diagram is also of fundamental interest, and it remains an amazingly rich and complex area of study. The main reason for this complexity is the abundance of parameters that define the system, such as the temperature, the magnetic field, the anisotropy, and the disorder. These parameters can be systematically varied in a controlled manner, making these systems a powerful medium in which to study phase transitions. The graduate students involved in this project will receive training in a wide range of experimental techniques. They will also gain valuable international professional experience early in their careers, increasing their adaptability and placing them in an excellent position to pursue careers in industry, national laboratories, or academia. %%% This individual investigator award is to a young, female professor at Western Michigan University for an experimental research project that focuses on understanding the role of disorder in determining the phase diagram of the vortex matter in high temperature superconductors. Vortices are quantized bundles of magnetic flux which penetrate a Type-II superconductor in the presence of high magnetic fields. The interaction of these vortices with defects is of great technological importance because defects can greatly increase the amount of current these materials can carry without energy losses. Since most applications of superconductors rely on zero-resistance, developing optimized pinning sites to prevent the vortex motion is crucial to advancing their technological impact. These systems are also a powerful medium in which to study phase transitions, an area of fundamental interest. The vortex matter phase diagram is a rich area of study because of the abundance of parameters that define the system, for example the temperature, magnetic field, anisotropy, and disorder. These parameters can be varied in a controlled manner over a much greater range than in typical solids. The collaborative nature of this project will train graduate students in both academic and national lab research settings, teaching them in a variety of state-of-the art-techniques. The international experience the students gain will enhance their ability to compete in the increasingly global market place. ***