Good afternoon: Department Seminars and Colloquiums for week of December 1, 2008 are as follows: Tuesday, December 2, 2008 at 2.30 PM* Joint Tufts/CfA/MIT Cosmology Seminar The Scale-Factor Cutoff Measure on the Multiverse Michael Salem Tufts University *refreshments served at 2:00PM in Knipp Library, Room 251 Robinson Hall, Room 250 Tufts University http://www-ctp.mit.edu/cosmo.html Friday, December 5, 2008 at 3:00 PM Anderson 206 Tufts University Physics and Astronomy Colloquium ?Unsolved Mysteries: Electron Pairing in High Temperature Superconductors? Dr. Vidya Madhavan Boston College The electron-electron interaction is normally repulsive. In some materials at low temperatures, this repulsive force is defeated and electrons feel an attractive force that binds them into pairs. It is the formation of these pairs that creates a zero resistance material: a superconductor. We now know that the miracle glue that binds electrons into pairs in conventional superconductors is phonons. But after two decades of intense research on high-temperature (high-Tc) superconductors, there is no consensus on the basic question: what is the mechanism that causes electron pairing? The ?high-Tc problem? remains one of the most important outstanding problems in condensed matter physics today. Even as we explore the possibility that pairing in these unconventional superconductors proceeds without the involvement of a bosonic glue, we have recently made exciting progress in identifying candidates that could potentially mediate pairing. I will present low temperature scanning tunneling microscopy data on the high-Tc superconductor Pr0.88LaCe0.12CuO4 (PLCCO) where we have discovered a bosonic mode at energies of 10.5±2.5 meV. I will discuss the possible origins of this mode and its implications for the pairing mechanism of the high-Tc superconductors. Refreshments at 2:30 PM in Knipp Library, Robinson 251
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colloquium flier Madhaven12-05-08.pdf
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