Comment to the paper 'In-plane spectral weight shift of charge-carriers in YBa2Cu3O(6.9)' by A. V. Boris et al., Science 304, p. 708 (2004)

摘要

Recently, A. V. Boris and colleagues claimed to deduce a decrease ofintraband spectral weight (SW), and a transfer of SW from intraband tointer-band frequencies, when optimally-doped or slightly underdoped cupratesbecome superconducting [A. V. Boris et al., Science 304, p. 708 (2004)]. Weshow that, while their data agree with others [H. J. A. Molegraaf et al.,Science 295, p. 2239 (2002) ; A.F. Santander-Syro et al., Europhys.Lett 62, p.568 (2003)], their analysis is flawed. They cannot disprove the results whichyield a superconductivity-induced increase of intraband SW, and a transfer ofSW from high to low frequencies, in underdoped or nearly optimally dopedBi-2212.