Ph.D. UC San Diego, 1969
Experimental research in two areas, low-temperature solid-state physics and surface physics, is carried out in our group.
The focus of our research in low temperature solid state physics is on novel transition metal, rare earth and actinide compounds which have unusual physical properties that can be traced to partially filled d-and f- electron shells of these elements. Most of the materials are prepared in our laboratory at UCSD where their transport, thermal, and magnetic properties are investigated at temperatures as low as 10 mk, at high pressures up to 160 kbar, and in magnetic fields as high as 10 tesla.
One of the main objectives of our research has been the study of superconductivity and magnetism, and the striking effects that arise from the interplay between these two phenomena. Part of our research has concentrated on the anomalous physical properties of certain rare earth and actinide compounds in which the localized f-electron and conduction electron wavefunctions are strongly hybridized. A remarkable subclass of these compounds consists of metals in which the conduction electrons have enormous effective masses as large as several hundred times the mass of the free electron. Heavy electron materials have attracted worldwide attention, because some of them display an unusual type of superconductivity that may be the analogue of the "triplet" superfluidity found in liquid 3He at very low temperatures.
Currently, the emphasis of our research is on copper oxide superconductors, some of which exhibit superconductivity at temperatures as high as ~130K, well above the boiling point of liquid nitrogen (77 K). These remarkable superconducting materials are of immense interest because of their potential applications in technology, and the possibility that a new superconducting electron pairing mechanism, different than the conventional electron-phonon interaction, is responsible for their spectacularly high superconducting transition temperatures.
Our research in surface physics is concerned with magnetism and phenomena involving the interaction between gas molecules and the surfaces of solids, such as chemisorption, catalysis, and oxidation. We have been particularly interested in the effect of magnetic phase transitions of metals on their oxidation kinetics and in oscillatory chemical reactions over transition metal catalysts.
Selected Publications:
Oscillatory Oxidation of CO over Pt, Pd, and Ir Catalysts: Theory. With B.C. Sales and J.E. Turner. Surface Science 114, 381 (1982).
Coexistence of Superconductivity and Magnetism. In Advances in Superconductivity. Ed. B. Deaver and J. Ruvalds. Plenum, New York, 279-346 (1983).
Partially Gapped Fermi Surface in the Heavy Electron Superconductor URu2Si2. With J.W. Chen et al. Phys. Rev. Lett. 56, 185 (1986).
Novel Types of Superconductivity in f-Electron Systems. Physics Today 39, 72 (1986).
High Temperature Superconductivity in Th-Doped Nd2Cu04-Y. With J.T. Markert. Solid State Communications 70, 145 (1989).
Evidence for Non-Fermi-Liquid Behavior in the Kondo Alloy Y1-xUxPd3. With C.L. Seaman et al. Phys. Rev. Lett. 67, 2882 (1991).