Date/Time
Date(s) - 27/10/2004
3:30 pm - 4:30 pm

Title: Inelastic X-ray Scattering: A new probe of condensed matter

Speaker: Dr. Young-June Kim

Institute: Department of Physics
University of Toronto

Location: ABB 102

Description:

Extremely bright photons generated at the new generation of synchrotron light sources have made a huge impact on various scientific disciplines ranging from biology to materials science. One of the exciting new developments is the use of x-rays in the field of solid-state spectroscopy. Inelastic x-ray scattering, analogous to the well-known inelastic neutron scattering, is a powerful tool for studying momentum-dependent collective excitations, such as phonons and certain electronic excitations. I will begin with an overview of the status of inelastic x-ray scattering, and then discuss a few specific examples to illustrate new scientific opportunities presented by this rapidly developing experimental technique. One example that will be discussed in detail is the electronic excitations in quasi-one-dimensional strontium copper oxide. In such one-dimensional systems, spin and charge degrees of freedom of the electron are decoupled and elementary excitations are described by the collective modes of spinons, holons, and anti-holons. In a recent inelastic x-ray scattering experiment, we have observed a continuum of holon and anti-holon excitations, which carries important information of spinon dispersion as well. These results will be compared with a theoretical calculation based on the extended Hubbard model.