THURSDAY, Sept. 20, 12 p.m. JILA Auditorium
Dan Dessau
University of Colorado, Boulder
Electronic Structure and Competing Interactions in Colossal Magnetoresistive Oxides
The doped manganese oxides (manganites) such as La2-2xSr1+2xMn2O7 display a wealth of exotic behavior, including metal-insulator transitions, ferro- and anti-ferromagnetism, nanoscale phase separation, and of course, colossal magnetoresistance. I will review some of the key physics concepts of these materials and then move to a discussion of some of our recent photoemission studies of these materials. In particular, I will show that the Fermi surface evolves in a non-monotonic way with doping, and how this is likely the result of a competition between various ordering tendencies, in particular those involving spins, charges and orbitals. Such competing interactions are generally believed to be one of the key ingredients for understanding the rich behavior of the manganites.