Seminar

Optical self-energy effects in the cuprates

Dr. Jungseek Hwang,
McMaster University,
Tuesday, March 7, 2006
Higgins 235, 2pm

High temperature superconductors (cuprates) are different from conventional superconductors in many ways. In conventional superconductors phonons act as the glue that binds the electrons into pairs. However, what the pairing glue is in cuprates is still an open question both experimentally and theoretically. Some proposed candidates for this glue include spin fluctuations (including a sharp magnetic resonance mode), phonons, polarons, or charge or spin stripes. In this talk I would like to discuss the issue from the point of view of optical spectroscopy. First, I will correlate a sharp mode found in the optical self-energy to features seen by other forms of spectroscopy: a kink in angle resolved photo emission dispersion curves, a well-defined magnetic resonance mode in magnetic neutron scattering, and a hump-peak-dip feature in tunneling spectra. Then I will discuss the temperature and doping dependence of the sharp mode and how its frequency varies from one cuprate to another. I hope to show, at the end of the talk, a hint of what the glue might be.