Daniel S. Dessau

Professor Dessau's research interests center around using advanced electron spectroscopies for the study of the electronic and magnetic structure of novel materials systems. Typically, one of the key aspects of these materials is the effect of inter-electron interactions, or correlations. In general, the physics of these systems is poorly understood, particularly when the interactions are of an intermediate strength. The class of materials that fits this description is growing rapidly and includes those with some of the most startling and useful physical properties, including superconductivity and giant or "colossal" magnetoresistance.

The important energy scale for the majority of interesting problems in condensed-matter physics is on the order of ten to a few hundred Kelvin, or 1-25 meV. Spectroscopies therefore must have an energy resolution of this magnitude in order to spectroscopy (ARPES) is just starting to reach these resolutions, and in the process has emerged as a very powerful tool for the study of the important low-energy scale physics. This is due both to the directness of the technique and the richness of the information the data contains. The energy, crystal momentum, and even spin state of the quasiparticle excitations are directly measurable by the peak positions, while the line-width and line-shape give information about the dynamics of the system.

Many of these spectroscopies are also surface-sensitive, with probing depths potentially as short as 3 Angstroms. This means that they are especially powerful for probing the electronic, chemical, and structural information of the surfaces and interfaces of materials systems.

Current materials systems of primary interest are the "colossal" magnetoresistive manganites and the high-Tc superconductors (HTSCs). A particularly important breakthrough we recently made in the study of the HTSCs is that the superconducting energy gap has a very strong in-plane k-space anisotropy, and this anisotropy is consistent with a d-wave order parameter . The publication describing this result had an impact ranking as high as #2 in all of physics, based upon citation frequency.
 

Selected Publications

• "Electronic Structure and Photoemission of Transition-Metal Oxides -- Mott Insulators and High-Temperature Superconductors", Z.-X. Shen and D.S. Dessau, Physics Reports 253, 1 (1995).
• "Key Features in the Measured Bandstructure of Bi₂Sr₂CaCu₂O₈+delta: Flat Bands at EF and Fermi Surface Nesting", D.S. Dessau, Z.-X. Shen, et al., Physical Review Letters 71, 2781 (1993).
• "Anomalously Large Gap Anisotropy in the a-b plane of Bi₂Sr₂CaCu₂O₈+delta", Z.-X. Shen, D.S. Dessau, et al., Physical Review Letters 70, 1553 (1993).
• "Search for a proximity effect induced gap in gold/high-T_c junctions", D.S. Dessau, B.O. Wells, et al., Applied Physics Letters58, 1332 (1991).

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