Special Condensed Matter Physics Seminar

Note special time!
4 p.m., Monday, January 22, 2007
Room 1201, Physics Building

 CeCoIn5: a "quasi-breakdown" of the quasi-particle paradigm at a quantum critical point

Johnpierre Paglione

(Department of Physics, University of California, San Diego)

Abstract:  The '115' family of cerium- and plutonium-based heavy-fermion compounds is host to a rich variety of strongly correlated electron behavior, including unconventional superconductivity, magnetic instabilities and anomalous properties which defy the long-standing "standard model" of condensed matter physics. In particular, the CeMIn5 system (M=Co, Rh, Ir) has received dramatic attention due to the tunable nature of its ground states: CeRhIn5 is a pristine, well-characterized antiferromagnet which can be pressure-tuned toward a superconducting state very similar to that of its cousin CeCoIn5, a 2.3 K ambient-pressure superconductor with many exotic properties centered around both pressure- and magnetic field-tunable quantum criticality. In this seminar, I will give an overview of our experimental investigations on this system, focusing on low-temperature heat and charge transport measurements which have revealed a profound breakdown of Landau's quasi-particle picture directly at the field-tuned quantum critical point of CeCoIn5. Highlighted by anisotropies in power laws, energy scales and the T=0 Wiedemann-Franz law, our observations point to a peculiar anisotropic destruction of the Fermi liquid arising from a novel form of criticality. I will also review several other studies, including 1) rare earth chemical substitution used to probe unconventional superconductivity, Kondo lattice and non-Fermi liquid behavior in CeCoIn5, and 2) de Haas-van Alphen measurements which characterize the Fermi surface transformation through composition-tuned criticality in CeRh1-xCoxIn5.
Host:  Yakovenko
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