Abstract:
The Fermi-liquid theory tells us that the volume of the Fermi surface measures the number of itinerant electrons. In reality, however, finite temperature and disorder may cause ambiguity how the Fermi surface is defined. For example, cuprate superconductors apparently have a "small Fermi surface" according to photoemission spectroscopy. In this talk, we discuss the temperature dependent evolution of the Fermi surface from "small" to "large", and resultant change in dynamics, by mainly using the Kondo lattice model. This study also raises a question about the meaning of "itinerant electrons". Our argument is based on highly accurate Monte Carlo results, which have been obtained recently with use of a newly developed continuous time technique.
Coffee and tea will be served 20 minutes prior to the seminar.