Infrared Studies of Cuprates, Superconductors, and Correlated Metals

w:\awards\awards96\num.doc 9705108 Tanner This experimental research project utilizes optical studies in the far-infrared through the ultraviolet wavelength range to clarify properties of normal and superconducting states of high temperature superconductors and related novel metals. An emphasis is on use of the spectra to study the doping-induced and superfluid spectral weights and their relationship to the transition temperature. Other issues include the non-Drude midinfrared absorption, the scattering of charge carriers, the superconducting energy gap and the effects of strong external magnetic fields. %%% This experimental research project uses the absorption of light to study the copper-oxide superconductors and related materials. The measurements, in effect, count the number of mobile electrons per copper and determine how many of these condense into the superfluid below the superconducting transition temperature. This provides important direct information about the superconductivity. The measurements are done over a wide wavelength and temperature range, and include measurements while the sample is subjected to a strong magnetic field. Results from this research may include unusual new effects or materials which may find new application in technology. This research project is interdisciplinary in nature and involves graduate students who will be excellently trained to enter positions in industry, government or education. ***