Probing the Electronic Structure of Overdoped Cuprates
University of British Columbia, Vancouver, British Columbia
Angle-resolved photoemission spectroscopy (ARPES) on the high-Tc copper oxides superconductors (such as La2-xSrxCuO4 and the Bi-cuprates) did provide us with crucial insights into the complex electronic structure of these materials. On the other hand, despite the intense effort, no conclusive agreement was reached yet on some of the most fundamental issues. In this context, important breakthroughs could come from the study by ARPES of Tl2Ba2CuO6+d (Tl2201): this system is characterized by a well ordered crystal structure, with very flat CuO2 planes far apart from each other, and a very high Tc,max=93K; in addition, it would also offer an alternative approach to superconductivity, i.e. from the very overdoped side of the phase diagram. Unfortunately, until now ARPES studies of Tl2201 were prevented by the lack of high-quality single crystals due to the difficulties of the growth process. Very recently, however, these difficulties were successfully dealt with and single crystals of unprecedented quality were produced at UBC, which gave us the opportunity of obtaining an extensive set of ARPES data from Tl2201 for two different doping levels. This study provided us with detailed information on normal state Fermi surface, quasiparticle dispersion, and symmetry of the superconducting gap, as well as preliminary insights on the effects of charge inhomogeneity, many-body, and quantum-critical phenomena in overdoped cuprates. These findings will be discussed in relation to what is observed on the under and optimally doped side of the cuprate phase diagram.