Date/Time Date(s) - 14/10/20093:20 pm - 4:20 pm
Title: Evidence for the Collapse of Single-Band Hubbard Physics in Overdoped Cuprates from X-ray absorption spectroscopy
Speaker: Dr. David Hawthorn – University of Waterloo
Institute: University of Waterloo – Physics
Location: ABB 102
Description:
In the high temperature cuprate superconductors, the electronic structure is commonly simplified to a single-band Hubbard model or t-J model â?? Hamiltonians that are perceived to include much of the essential physics of the cuprates and are theoretically justified by a Zhang-Rice singlet model of the cuprates. Although many experiments including x-ray absorption spectroscopy support this picture at low doping, measurements of on the overdoped high-temperature superconductors Tl2Ba2CuO6+δ (Tl-2201) and La2−xSrxCuO4±δ (LSCO) reveal a striking departure in the electronic structure from that of the underdoped regime. This suggests either a breakdown of the Zhang-Rice singlet approximation and a loss of correlation effects or a significant shift in the most fundamental parameters of the system, potentially rendering single-band Hubbard models inapplicable to overdoped cuprates. In addition to discussing these x-ray absorption measurements, I will also touch upon our recent efforts to build a resonant soft x-ray scattering facility at the Canadian Light Source in Saskatoon.