Superconductors are materials that conduct electricity without any resistance, which means there is no loss of energy when a current flows through the material. If the temperature at which a material becomes a superconductor (its Tc) were closer to room temperature, it would be practical to use superconducting transmission lines to transfer electrical power, among other applications. The problem of high-Tc superconductivity is surpassed by few, if any, other unresolved problems in contemporary physics - in view of its richness, complexity, impact on other fields and potential technological importance. This individual investigator award supports a project aimed at making significant advances in this challenging problem. A comprehensive set of infrared (IR) studies of a recently discovered family of high-Tc superconductors, the "pnictide superconductors," will be undertaken. The project is enabled by a confluence of several factors including recent progress in the development of instrumentation for IR optics and a newly emerging availability of well characterized single crystals of pnictide high-Tc materials which are ideally suited to address a number of specific long standing issues. Equally important for the success of the project will be a dedicated effort to recruit talented graduate students into the research group, including students belonging to groups currently underrepresented in science. The latter task will be accomplished by engaging in research undergraduates from institutions with a large fraction of students belonging to underrepresented groups. Furthermore, the PI will continue offering a course on "Ethics in Physics" tailored for upper division undergraduate and graduate students at UCSD. The purpose of this course is to inspire, from the very beginning, an ethical vision of scientific work thus raising students' awareness of the tremendous impact their work can have in society.
This individual investigator award will support a new effort on infrared studies of recently discovered pnictide high-Tc superconductors. The proposed experiments: 1) will deliver critically important insights into the essential characteristics of the normal state of pnictides including the role of proximity to a magnetically ordered state and strong coupling of mobile charges to both lattice and magnetic excitations; 2) will produce a detailed experimental picture of the formation of the superconducting condensate including the evolution of both the energy gap and superfluid density in these anisotropic systems; and 3) will provide information needed to critically assess the role of electronic correlations in both exotic normal state properties and superconductivity. This project expects to disentangle material-specific properties of particular families of pnictides from the intrinsic characteristics generic to the entire class of iron-based high-Tc superconductors. The work will facilitate training of graduate students and provide opportunities to engage undergraduates in scientific research.
