The Electronic Structure of the High Temperature Superconductors Studied by Angle Resolved Photoemission

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9624048 Campuzano Angle-Resolved Photoemission will be used to study many- body effects in high temperature superconductors. The technique will provide clues on (1) the nature of the spectral function of the quasiparticles in the normal and superconducting states, (2) the momentum distribution of the normal and superconducting states, (3) the dependence of the quasiparticle lifetime on temperature, momentum and energy, (4) the relationship between the van Hove singularity and the normal and superconducting properties, (5) the nature of the superconducting gap function in the clean limit. Limited preliminary results indicate that these properties exhibit unusual behavior, and that the high temperature superconductors still have many interesting Physics surprises in store for us. %%% Angle-Resolved Photoemission will be used to study many- body effects in high temperature superconductors. In this technique, the sample is irradiated with ultra-violet light. This causes the electrons in that sample to be ejected. By analyzing the energies of those ejected electrons, the state of the electrons in the sample can be obtained. This information can, in conventional materials, lead to understand how the material carries current, and how it becomes superconducting upon cooling. However, high temperature superconductors do not behave like conventional materials. The electrols in these materials interact with each other and the motion of one electron is strongly correlated with the motion of other electrons. Materials in which this occurs are called "Strongly Correlated Materials". The proposal seeks to provide a direct measurement of the "spectral distribution". The latter measures the probability of adding or removing an electron from the sample. This will lead to the understa nding of the novel electronic properties of high temperature superconductors. ***