Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 30: Superconductivity: Twenty Years High-Tc Cuprates - Recent Progress
TT 30.12: Vortrag
Donnerstag, 30. März 2006, 17:00–17:15, HSZ 02
Optical spectral weight shifts and sum rules in cuprates: role of strong correlation — •Alessandro Toschi1, Massimo Capone2,3, and Claudio Castellani3 — 1Max-Planck Institut für Festkörperforschung, Heisenbergstr. 1,*D-70569 Stuttgart, Germany — 2Istituto dei Sistemi Complessi del CNR, Via dei Taurini 19, I-00185*Roma, Italy — 3Dipartimento di Fisica Università di Roma "La Sapienza" piazzale Aldo Moro 5,*I-00185 Roma, Italy
We show that many unusual features recently observed in the optical spectroscopy experiments on the high-temperature superconducting cuprates can be simply understood as arising from the vicinity to the Mott transition, without invoking more involved and exotic mechanisms. More specifically we compare calculations based on the Dynamical Mean Field Theory of the Hubbard model with the infrared spectral weight W(Ω,T) of La2−xSrxCuO4 and other cuprates. We find that most of the anomalies observed in the T- and the doping dependence of W(Ω,T) with respect to normal metals can be ascribed to strong correlation effects. Moreover the variation of weight at the superconducting transition in optimally and underdoped cuprates, that can be interpreted as a gain in kinetic energy, is accounted for by a strong-coupling (almost bosonic) superconductivity, while the overdoped materials behave more like standard superconductors.
[1] A.T., M. Capone, M. Ortolani, P. Calvani, S. Lupi, and C. Castellani, Phys. Rev. Lett. 95, 097002 (2005)
[2] A.T., M. Capone and C. Castellani, cond-mat/0509188, to appear on Phys. Rev. B