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Events on Thursday, March 4th, 2010

R. G. Herb Condensed Matter Seminar
Fermi Surface investigation across the quantum critical point in CeIrIn5 and CeCoIn5 via de Haas van Alphen measurements
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Cidgem Capan, UC-Irvine
Abstract: A quantum critical point (QCP) is a continuous ground state transformation at T=0, tuned by an external parameter such as pressure, chemical doping or magnetic field. The critical behavior associated with this T=0 thermodynamic singularity may be the common feature underlying the similar phase diagrams found in a wide variety of strongly correlated systems, including cuprates, ruthenates, heavy fermions and iron pnictides. Among these systems, the heavy fermion compounds, rare-earth materials exhibiting large effective masses, have played a particularly important role for investigating the evolution of the Fermi surface across a QCP. In these materials it is the competing tendency of conduction electrons to screen or to mediate a magnetic coupling among the f-electrons that ultimately leads to a QCP. The important and still open question regarding the underlying mechanism of the QCP is whether the Fermi surface volume changes abruptly at the onset of magnetic ordering. Following a broad introduction, I will focus on two heavy fermion superconductors: CeMIn5 with M=Co,Ir. These recently discovered compounds illustrate well the shortcomings of our current understanding of quantum criticality: despite the thermodynamic and transport evidence for non-Fermi Liquid behavior in these systems, their Fermi surface, as investigated by de Haas van Alphen effect, does not show a drastic change across the putative QCP. The implications and possible scenarios will be discussed.
Host: Natalia Perkins
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