Physics Colloquium, January 17, 2006

The strange properties of the pseudogap in the high temperature superconductors: A photoemission view

J.C. Campuzano

University of Illinois at Chicago

The high temperature superconductors present a challenge to our understanding of materials, as there appears to be no satisfactory description of their behavior in terms of text book concepts in condensed matter physics. After an introduction to the technique of angle resolved photoemission (ARPES), I will show examples of the unusual behavior of electrons in these materials. For example, there is considerable experimental evidence that the elementary excitations cannot be thought of as simple electron wavepackets, or quasiparticles, as in conventional metals. More mysterious still is the pseudogap, where low energy electronic excitations are depressed altogether as the Fermi surface vanishes in a most unusual way, leading to an even stranger ground state, one in which gapless excitations occur at only discrete points in momentum space.

4:00 p.m., Physics Research Building (PRB), Room 1080

Reception at 3:45 p.m., Atrium, PRB